Had my PJS-1000 electric motor develop a knock, just like a gas engine, now that really got everybodies attention! :) Got so hot it locked up and couldn't put a finger on it.
Pulled it apart and found the rear bearing bad. A flying buddy told me he'd punched the bearings out of his gasser and simply went down to the local bearing store and picked up some new ones. Hell, nothing to lose, so got a skinny punch that when inserted in one end it would catch the shoulder of the bearing at the opposite end, couple of taps and out it came. No problem getting replacements from the bearing store, just a few days wait.
Haven't got a chance to try it yet, but feels good. Almost deep sixed it and had gotten a new AXI to take it's place before getting the rebuild advice, but thought I'd share the thought. Two new bearings $8.00 vs. new motor $80-$100, not much to lose if it doesn't work......