When the spin cycle starts, within a few moments it stops. I've verified that the thermal cutoff switch on the motor is engaging (open circuit). After it cools and disengages, it will attempt to spin again and repeat the cycle. I'm not certain but I don't think it is reaching full spin speed.

I replaced the clutch band and brake cam, and also replaced the motor, and it still does the same.

The wash cycle runs normally, and I don't notice any strange noises or anything. Also, the underside and floor is clean, no oil leaks.

Answering my own question, maybe it will help someone with a similar problem.

I disassembled the timer module and found that one set of contacts had completely fused together. I was able to separate them and clean them up enough to try it out, and that fixed it.

Good enough for a quick fix, but I still plan to replace the timer.