I know how to test a motor, but....

I would check isolation of the armature windings at the commutator to the shaft.  It should be open (high resistance).  Check continuity between each commutator segment (1-3 ohms using and analog DVM).   Also check the brush tube nuts (if a flat face commutator)  and brass straps to ensure they are not shorting to the frame or shaft.  And, the tab for the pickup can sometimes be to close to the solder points on the commutator and will short as it rotates.

If it’s a MTH motor, they had problems with centering the armature in the field, which causes them to bind.

It's not a MTH...its an original Lionel motor.  I don't have the pickup rollers attached, so that is not the issue.  I did check the brass tabs and nothing is shorting out when tested.  What is an analog DMV?  How do I perform such a test?

THanks,

Greg

You need to set the multimeter to continunity where you get the "beep" if you touch the red and black probes together.  Then check each comuntator segment for short to the shaft, and to each other.  This will see if you have a bad armature or not.  If run hot in the past, its possible a segment is shorted to the shaft or to another segment which would render the motor dead.  A replacement armature or having yours rewound would be required.   AD

if bench testing, touch hot to the insulated end of field, neutral to a brush lead. Ground the other brush lead to wherever the field is grounded ( usually the frame)   Motor should run in one direction……to change direction, swap brush leads, put the neutral on the other brush lead, and then ground the other,….the motor will change directions,…..if you got the motor to run, it doesn’t sound like you’ve got a short,…if it ran crappy, you could have a bad segment, or one pole shorted to armature shaft,….

Pat

SO I FOUND THE CULPRIT!

When I had removed the old solid wires from the terminals on the motor, a small piece of the wire broke off and stayed connected to the post of one of the brushes.  I failed to notice it because it was "hiding" under a washer secured by a nut.  When I started to look VERY closely at everything, I discovered the small piece of wire still connect to that post was just barely touching the metal part of the frame!  After I removed the wire and tested the motor, it worked perfectly!

Of course, I am relieved now, but kicking myself for letting a small piece of wire take up half of my day and drive me crazy in trouble-shooting! LOL

Thanks for all of your assistance with this- much appreciated!

Greg