Here's a tip for those of us who've struggled with these motors binding up.
Me? One solution I've never seen offered is that stakes anchoring the field frame to the top of the motors chassis have come loose over the years thus causing the armature to bind against the Field's frame.
The bad news is you need to grind off the side truck's staking tabs to access the Field's stakes. But once removed the stakes are easily accessible (note these stakes aren't visible with the truck frames attached nor are they shown in Lionel documentation - as the motor wasn't sold separately)
At this point, I also suggest pulling the wheels and re-staking all of the stakes holding the motor's frame together. Once done, reinstall the wheels & idler gears and reattach the truck frames with your preferred adhesive.
I performed this on a motor that only ran poorly in one direction. It now runs in both direction as good as these motors are able to run (they are not one of Lionel's "Crowning Acheivements" 😉)
Hope this help
