I purchased a Santa Fe 484-485 and 486 used. I thoroughly cleaned both chassis on the 484 unit removing petrified grease and crud. One of the worm gears was stripped. I replaced it with new. Axle holes on both motor units were good. Armature bearings were good. I replace the brushes on both motors and lubricated both motor armature bearings and gears properly. I replaced both thrust pads on each motor. I disassembled and cleaned the reverse unit and replaced both fingerboards. Checked all wiring connections and resoldered the old ones. After my first track stand test The motors ran okay forward and reverse but there seem to be no high end power. I then replaced both brush holders with brand new and new brush springs. The track stand test produced a little better results but I could Tell it wasn't reaching high enough RPM. I reassemble the body to the chassis for a test on my layout. The 484 ran okay by itself but nothing to brag about. I added the 485 and and 486 units. The 484 struggled to pull them around the track. Again I dismantled both motors checking all wiring centering of the armature in the field and I'm still having the same problem. Do these alco armatures tire after a while? The only test I did not perform was an ohm test on the commutator of both motors. I didn't feel it was necessary because both motors are running evenly but are not getting the power that I'm sure they have. I think I have exhausted every procedure possible except replacing armatures and I really don't want to go there if I don't have to. Any thoughts out there?