Mark -
I haven't heard from Jed in the last couple days, but we took the discussion off-line as you can see above.
Turns out the culprit was the T-bearing retaining collar, which was stuck on the agitator shaft about 5 milimeters above its normal position (even without the set screw), thus the whole drive was being forced to sit too high by the same distance.
We discussed cleaning and lubing the spin tube, bearings, etc. I don't know what the final result is or was.
Gordon