I've seen it discussed somewhere on the forum, but am defeated using the search function.

I have some considerable play between the back pulley and the rear wheel hub, not related to torque of the axle bolt or to tightness of the pulley to the cast assembly that holds it to the bumpers in the hub. The play is in the assembly. It is associated with some noise when riding... not a grinding but a howl... and it's not from belt misalignment.

Is this a bad bearing on that side?

I guess I will try Dave's pieces of floor mat on top of the bumpers... not able to machine bushings...