My original problem was a harsh squeal during the spin cycle. I had a service guy diagnose the problem and since the parts only were under warranty I did the replacement myself.
Personally, I think it was the bearing only, but they sent me a transmission, bearing kit and the spin nut at the base of the tub so I replaced everything.
I suspect that you are correct that the problem is down at the pulley. But I can't figure out what the problem is. When I took the pulley apart, it kind of exploded and the parts went everywhere so I'm not positive I got all the parts back in the right order (there were many washers, etc.). Also the unit that engages the spin (on the inside of the pulley) could have been installed two different ways. Perhaps I got this backwards?