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Also Doctorwayne is very knowledgable on these.  I have only taken 2 apart.  Be careful when you get to the remove the boiler step. Dont remember where I found this, but here you go: I still see posts asking for help to repair this otherwise fine engine. Those thin motor wires are the culprit which is an easy fix but that boiler removal--hoo boy. So here is a reprint I posted from a few years back on a newsgroup. I incorporated several other good instructions from other posters into it, including Athearn's. BTW when I found out about the cracked gear in this loco, almost ten years after I bought it, I emailed Athearn and they sent me a brand new gear axle with drivers attached, free of charge. They are great people! Anyway here's the boiler removal instructions from rec.models.railroad, 2002: Repairing and weighting Athearn Mikado--Update For the past three years a number of us have experienced problems with the original issue Athearn Genesis Mikado: poor traction, the stiff umbilical, and engines suddenly gone dead. I finally got up the guts to take mine apart and solved all three issues. My thanks to all those before me who have posted their knowledge and know-how dissecting the Mike. I'm an electrician so I'm adding all electrical knowledge of this adventure that I've learned. I recommend a mandatory repair for every Athearn Mike owner to re-do the two wires attached to the weight halves. Many of these connections, if they don't break off entirely, are hanging by a strand or just making a pressure connection. The resistance buildup  would affect engine performance for the life of the motor. I thought I could get away with weighting the loco externally, because the instructions I had so far read about disassembly sounded formidable.  After manipulating the wires between cab and tender one day I ended up with a dead loco. I decided a round trip to Korea and back for the patient would take too long, so I printed up Athearn's disassembly instructions (and several others from rmr posters) and jumped in. I ended up taking my Mike apart three times and it turned out to be a piece of cake once past the fear stage--like so many other things in life. Here are Athearn's instructions with my comments (*) interspersed--because Athearn left out some critical details. 1. Take off the cab . . . *Remove the two cab handrails first. a.  lift the rear of the cab to release the two rear tabs (small screwdriver carefully inserted at bottom rear of cab will help) *Take your time--first removal is tight. Alternate from one side to the other with the screwdriver or exacto blade. b.  insert screwdriver at front side of cab between bottom of cab and walkway and carefully spread side of cab away from boiler to release small tabs at front bottom of cab (much easier to do than to describe). c.  lift cab straight up and off of boiler. 2.  Remove smokebox front and unplug two wires (use sharp tweezers to pull plugs straight down). *Take note of the polarity for later--white goes to white. 3.  Remove the boiler to pilot deck supports (we'll get the correct term for future use) *These are the black diagonal rails between boiler front and pilot. 4. Remove screw from bottom of frame that goes up into stack *Remove the black gizmo just forward of the walkway on the engineer's side where the silver section starts. Pull it straight out with a needlenose. It goes back the same way. 5.  Insert screwdriver at rear of boiler above walkway and carefully pry boiler rear upward.  Do this on both sides to release the tabs that hook the boiler to the walkway. * With a small implement push those black tabs in alternately to help release the boiler. 6.  THIS IS THE TRICKY PART .  .  .  after rear of boiler is released, lift rear of boiler to clear the weight, then CAREFULLY slide the complete boiler forward. May need to wiggle it as you slide it forward.  Boiler comes off, and you have the innards exposed. * The boiler will not break, even though it feels like it will. Tip the rear end as hard as you like until it just clears, then slide the boiler SLOWLY forward with a side to side wiggle. At the same time gently squeeze the front of both walkways inward to release the tabs gripping the inside edges of the boiler front. 7.  To take out motor and boiler weight, there are four screws to remove. Two screws are at rear, with red and black wires attached.  Two are on each side near front of weight, above walkway, just behind centerline of axle of first driver.  Take out these four screws and motor/weight assembly comes out. *First the wiring fix.  (I recommend) cut off the black tubing completely. It's too stiff and derails the tender. The green, yellow, and violet wires are not connected to anything and are for optional DCC functions. Pull them back over the DCC plug and secure with electrical tape. Tightly tape the remaining wires with a short piece of black vinyl electrical tape. I was able to flatten the bundle to reduce the profile. * (Do not re-use the factory connectors!) This is a finely crafted loco but the wire connections to the weight halves are extremely delicate and unreliable. The solder connections on mine were both broken. When it comes time to reassemble, clip the wire ends clean and strip enough insulation (3/16") from each one to wrap under the screws directly, now using the connector as a washer between screw head and wire. Twist the strands tight and pre-form the stripped wire into a tight circle. Position the loop over the screw hole. Insert the screw and tighten. Point the connector shanks straight down. The red wire goes to the engineer's side, black wire to fireman's. This may need the patience of a watchmaker, but take the time to make a good solid connection or it's disassembly time again. This is your main connection between the drivers and motor--it's important. *DO NOT CUT THE UMBILICAL OFF because the red and black wires go through the DCC plug and come back as orange and gray for the motor. Even if you spliced these, you still need the DCC plug for the headlight directional diode built into it. *Remember--the black weights are electrically live so depending on where you insert lead to add weight, it will short out the loco in any region bordering the two halves. Either tape the weights appropriately or wrap the lead with tape. *THE LEADING TRUCK USES A FIBRE INSULATING WASHER BETWEEN FRAME AND SPRING. IF YOU REMOVE AND THEN REPLACE THE SPRING, DON'T MISTAKE THE FIBRE WASHER FOR THE METAL WASHER OR YOU WILL CREATE A SHORT! The wiring harness of the Genesis Series USRA 2-8-2 Light contains nine (9) wires.  They are used as shown below: Gray     Motor negative Orange   Motor positive Red    Right rail pickup (engineer side) Black   Left rail pickup (fireman side) White   Forward light Yellow  Reverse light Blue    Light common Green   Function 1 Violet  Function 2 *That ends Athearn's info. Here is how I weighted my Mike, which I guess applies to the Pacific too. I used the experience of  those before me and a little of my own added. Note: although lead is ideal, for health reasons I used copper stock which is almost as dense. Fill the sand and steam domes with lead shot or lead pieces or fishing sinkers. Seal the lead in with ductape. Make sure the lead doesn't protrude too far out of the recesses or the boiler won't fit on. I didn't feed lead shot into the cylinders out of fear of the rods jamming. Do this at your own risk. Obviously don't fill beyond the level of the rods, but if the shot balls pile up at one end you risk a toasted motor. Seal the bottom of the steam chest (where the screw came through) with ductape, enough to also drape up the sides, covering the cylinder access holes. Fill this with lead shot and seal the top off with more tape maintaining a clear curve for the boiler to rest on later. OR, skip the ductape and shove lead sheeting diagonally into the cylinders above the rods, then pile up little square pieces or sinkers to fill the chest. You don't need to replace the long screw. The tiny screws at the bottom of the chest need to be insulated--they are common to the frame. Cut lead sheeting or sinkers to fit between the leaf springs above the drivers. Don't go too thick or the boiler won't sit right. Paint the lead black. This arrangement is not prototypical but it's hard to notice.  You can pile a good ounce into this area. Likewise under the driver assembly. Flip it over. Thin lead sheeting can slip under the brake mechanism truss rods, between the first drivers, and between the cylinders. They need to be glued. To remove the brakes pop them out of their pegs near the drivers. The little truss rods are fragile and will snap if bent too far. Paint the lead black. The two tiny screws in the middle by the manufacturer's info plate need to be insulated. More thin lead sheeting can be curved and slipped under the boiler weights after this section is mounted to the drivers. Tape the lead up with electrical tape to prevent a short. The pieces cannot extend above the level of the walkways or the boiler won't fit right. After the boiler is reassembled, lead sheeting can be curved and shoved between the boiler walls and the weights, and around the front of the boiler. They need to be insulated with tape first. Make sure it's a loose fit and accessible to pull out or the boiler will never come off again. Leave room to re-connect the headlight and for the smokebox front. Before mounting the cab, glue or tape more curved lead under the cab roof. Not too thick or the cab won't fit right. Paint it black. A feedwater heater can be made from lead and glued forward of the stack. An air tank can be placed at the rear of the pilot between the ladders. (credit goes to Hazen for these two) Or one could fashion plastic cylinders and fill them with lead. That can add a good amount of weight. The Athearn Mike weighed in at just above twelve ounces out of the box. After I was done adding just copper,  I increased this to nearly fourteen ounces. Using lead will probably give you fifteen. 2-3 ounces added is ideal. (according to Hazen) The loco no longer slips going up even a 10% test grade. Good luck to all. Reply post later on from different guy who has a bunch of these. <div style="margin:0in 0in 10pt;">Actually, for Step 5, simply squeeze the boiler immediately above the back end of the running boards, and as close to them as possible, to release the tabs in the firebox.  This way, there's less chance of breaking the tabs than by prying.</div>
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