Bird nested motor??? Well, I don't know about back east anymore but what I do is every once in a while is go to some god forsaken hell hole out in the middle of no where (Glamis California seams to be a favorite) and with torch in hand climb under the offending locomotive, light the torch and burn a hole in the bottom of the gear pan, then slice a big chunk of the pinion gear (with out getting the armature shaft, thats a big no-no) so it clears the bull gear. climb back out after dowsing the burning crator grease with the Co2, clean my self up and head back to the diesel shop.Axle is now free to move locomotive at track speed to the nearest drop table. BTW, one of these was (at the time) a five month old SD-70.