I had cracked gears on both my GP-7's and all of my FA-1s. It's an across the board problem.
Usually the symptom is that the loco wil move a short distance, then "bump" or thump, sometimes hesitating right after the bump. Sometimes it won't move after the bump,unless you crank up the throttle,then it goes, thump tump thump thump thump,etc.........If they get real bad,they can go way out of gauge,and cause a short.
Athearn parts fit, and are a different plastic.
If I recall correctly, and it is a big if, the P2K BL2 is one of the engines that had the bad gears back in the LifeLike days. This is the same problem that plagued the GP-9s.
I would try swapping the axles with the sister unit. The bottom of the gearbox comes off pretty easily, and then you can just lift the wheel/axle assemblies out and swap them. If the problem goes away, replace all the axles on both engines. Sooner or later, they will all fail, and there's no sense doing this twice.
It takes an iron man to play with a toy iron horse.
You are very fortunate that you have an identical unit. I would pull parts off the "known good working" unit, and use them to replace parts or assemblies on the problem unit. Sooner or later one will fix the problem. I call that "extrme trail and error scientific method troubleshooting". If you suspect the motor, start with the motor. I'd also mark each item I tested with a dot of paint or a sharpie, so I know which unit it came out of, and I'd document which parts tested good, or had no effect.
Sometimes cracked gears are very difficult to spot. Fortunately you can swap the trucks fairly easily.
The troubleshooting method also works backwards. If you want to "solve for" the motor, you could put the motor from the problem unit into the working unit, and see if the problem follows the motor, or the rest of the chassis.
Good luck.
I have one of the original P2K BL-2 models that is acting very similar to your experience. I know the decoder is good (A new TCS T-1), the gears and wheels have been replaced, but it growls and jerks, indicating that something is wrong with the motor. Some day I may get around to replacing it, but for now I have just put it away.
A simple way to determine if the motor is the problem would be to remove the drive shafts from both trucks and see how the motor runs alone. If it sounds okay, put some finger pressure against one of the flywheels and see what happens. If no problems here, then it's more likely to be a decoder or gear issue. I suspect that you do have cracked gears and don't know it. I replace P2K gears with Athearn.
alco's forever!!!!! Majoring in HO scale Minorig in O scale:)
I would swap out the decoder with a known good decoder or better yet remove the decoder and wire the motor to the pickups. Then do a stall current test and see if the motor is bad. My guess is a bad decoder.
Pete
I pray every day I break even, Cause I can really use the money!
I started with nothing and still have most of it left!
I have an older P2k BL2 that is giving halting, slow/pulsing response, especially compared to an identical sister model. It also has a loud pulsing/binding noise when in motion.
I have checked everything I can think of......axle gears ok, commutator & brushes are ok, gears in good order and clean and lubed just right, shafts ok., worm gears ok.
Wheels at the right gauge and clean, wheel bushings are free wheeling.
Decoder reset to defaults.
All I can think of is that the motor is flawed. On a bench test it seems to run ok, but there is play in the motor shaft...I can move it back and forth about a sixteenth of an inch or so.
I think this may be normal, though. I can't see anything that would lead me to want to replace the motor. Although I have a couple on hand and am tempted to give a new motor a try.
Are motor problems so suble that they can't be detected with the naked eye so to speak?