(05-14-2014, 10:20 PM)Highpower Wrote: Got the new bearings in the mail today. These have no markings on them anywhere. But they are the correct size so that's what counts.



Installed the rear bearing on the armature shaft, making sure that it was in the same spot as the old bearing. 7/64" from the square edge of the shaft. The shaft end is rounded. (I measured it before removing the old bearing.)



Then installed the front bearing in the end bell, put in the retaining ring and crimped it back into place. You have to carefully tap around the inside lip of the end bell (red arrows) to open it up in order to remove the original bearing.



Piece the motor back together and insert it and the speed controller back into the case halves. Re-install the brushes and it's done.



Final results: Mixed.
The good news - the motor runs quiet again (well, for a Dremel) with no screeching noise, and the nose of the tool stays cool. It would heat up quickly with the bad bearing and become uncomfortable to hold.

The bad news - I didn't fix my speed control issue. It lost most of it's variable speed right before the bearing went bad. While I had it apart I flushed out the rheostat(?) / potentiometer(?) with some contact cleaner (DeOxit-5) in hopes that it would revive the mid range of the speed control. But no luck on that front. The speed dial is marked 1-7 and from 1 to about 5-1/2 the tool only runs at slow speed. From there it ramps up quickly to full speed at "7". It's not a linear increase in speed over the entire dial.

In the end, it's basically a one speed tool now, but at least it's usable again. It will make a good "loaner".