OK, I ran my ETEK for a bit and the rotor started binding on the brush-side magnet. So I started looking for slop.
The magnets are located on the two housing halves. The rotor is located between them with the bearing and the shaft, along with some shims and a bearing lock plate, on one end only- the sprocket end (as opposed to the brush end). So, there’s where I figure there has to be some slop.
As far as I can see, the shims and the circlip seem OK. The shims measure out at a perfect .010 each, and the circlip fits snugly in it’s little circlip groove. The bearing has a bit of slop from side to side, so I’ve ordered a new one. I’m going to hazard a guess that it’s moving .015 or .020, at the most. I figure it can’t hurt to just plop a new one in.
But here’s what I found that may actually be significant. The bearing locking plate, on the inside of the housing, doesn’t seat up against the housing. Here’s what I mean.
This is the bearing sitting in the housing.
The outer diameter of the bearing is flush with the face of the housing. Here’s the plate, sitting over that face:
That, once it’s bolted in, should hold the bearing flush with the face. The problem is, it doesn’t. The plate is slightly larger in diameter than the faceplate relief. Here’s what it looks like from the other side, with the bearing removed, showing the space between the plate and the face. It measures out to about .035.
…corresponding to the same depth of the relief on the inside between the outer casting (where the plate is sitting) and the inside face (where the plate should be sitting):
So, it should be a simple fix to just grind down a little of the edge diameter of the locking plate so it has a better fit. I’m not at all convinced that this will be enough to keep my rotor from binding, but it certainly isn’t right. Stay tuned.
For the record- this is a “Manta” ETEK motor from eBay- reportedly never used, and “remanufactured”.