Bowser DC-71 motor

[nachoman]

Hello all -

I recently picked up a 25+ year old Bowser 2-8-0 kit.  It has the DC-71 open frame motor. 

The kit has gone together well so far, but upon opening the motor I noticed lots of "magnetic dust" on the magnet.  I cleaned as much off as I could by vacuuming and compressed air.  Upon bench testing the motor detached from the chassis, it is overloading my Tech II power pack almost instantly when I get above 1/4 throttle.  When it overloads, the motor is very hot (more than just warm - but not to the point of smoking). I know these motors are current hogs, but I think this pack should be able to handle it.  I cleaned the commutator and brushes, and the armature spins freely.  The armature does not look damaged at all from a mechanical standpoint.  I tried replacing the magnet with neodymium magnets, but the result is the same.  The motor otherwise starts fine and runs smoothly at low speed.

Anything else to check here before I call this motor dead?  I may fiddle with the spring strength on the brushes, but the only other thing I can think of is that the armature has a short somewhere in the windings.

Thoughts?  I contacted Bowser, but if I have to replace the motor I will probably upgrade to a can motor to reduce current draw.