Took apart the pump to check the components. Switches, linkages, etch looked ok. There is a spring washer between the bearing and housing that looked worn. When I put it back together, I left out the spring and pump was noisy in both speeds. When I reassembled it, the noise went away! I will get a new spring and replace it if the noise starts again. Any ideas where I can get parts for AO Smith motors?

Thanks for sending me in the right direction!