Athearn N scale FP 45 changing from Mchenry couplers to Micro-Trains 1015 and 1016 couplers:
I used a Micro-Trains 1015 in the rear and a1016 in the front. If you wish a closer coupling you could use a 1015 in both locations, but may need to trim the coupler trip pin of the locomotive coupling to it as it will hit the snow plow on the unit with the short coupler.
I checked the couplers with a Micro-Trains NMRA N scale height gauge and the couplers aligned.
The model may be turned upside down in the case the engine came in as there is a depression that clears the air horn in the lower plastic cradle.
Remove the Mchenry couplers by removing the screw. Save the screw it will be used to install the Micro-Trains coupler later.
With the Mchenry coupler removed turn the model upright and file a very small amount of plastic from the lower surface of the shell coupler opening, only enough to clear the Micro-Trains coupler.
Slide in the Micro-Trains coupler into the pocket and insert the screw (you removed from the Mchenry coupler) align it with the threaded hole in the Athearn N scale FP 45 secure the coupler with the screw. Don't tighten the screw too tight as it will strip the threads in the plastic.
You may want to remove the shell but it is not required. If you do remove the shell you must remove the couplers first, then slide flat thin tooth picks between the shell and mechanism to release the shell.
I used a square nosed micro needle file (Micro Mark Item # 83180 3/16” wide) to file the lower surface of the shell pocket. If you don't have one you will probably need to remove the shell or purchase a file.
I used a small needle nose pliers (Micro-Mark Item # 60399) with the 90 degree bend at the tip to grip the shank of the screw which made it easier to install the screw in the coupler box.
My hands don't work as well as they once did so the pliers are my answer. The pliers also work for truck pins.
Tools required:
small electronics screw driver set with small 0 Philips screw driver bit Micro-Mark Item # 28106.
The Micro file set is Micro-Mark Item # 83180.
The pliers set is Micro-Mark Item # 60399.
Parts required:
Micro-Trains couplers 1015 or 1016 (1 ea. If using 1016 for front and 1015 for the rear) (2 ea. 1015 if using it for front and rear)