Frankford Arsenal used a really crappy quality cheap motor. It's an open C-frame style. No bearing to speak of, and they often wear through the end plate of the frame and die. The cost of buying a motor is about the same as buying a whole replacement tumbler unit. I tried to source them. Had no luck with cost.
The Berry's/Cabela's tumblers use the same style motor but theirs have actual bearings in them. I haven't killed one yet and I run 3 of them nearly all the time.
When my Midway 1292 and Frankford tumblers' motors died, I repowered them with a Broan bathroom fan motor from the home improvement store.
Cost is about $15 or so. Cut off the plug and wire-nut your power cord onto the wires.
It's not as big, but it will bolt in place. The shaft is a bit smaller but the weight on the shaft fit after a bit of metal foil was wrapped around the shaft, and the bathroom fan motor kit comes with a plastic bathroom fan blade that just fit inside the tumbler base so it runs really cool now.
The drawback is the Broan motor is smaller, does not vibrate as violently or shake the tumbler as much as the old motor.
What it is now is a perfect tumbler with some corncob to use to tumble the case lube off of resized and trimmed rifle brass, it's gentle so it won't ding up the case mouths I just chamfered and deburred.