Turned out to be bad bearings in the blower motor. Bought a motor and replaced it. No problem except removing the old fan blades to reuse. Finally drilled out the old motor shaft which then allowed me to drive it off the old motor. The fan cage feels extremely brittle. I disassembled the old motor which allowed me to drive the shaft out with out putting pressure on the blade. Hope that's one I don't have to do again soon.