Typically if high only its the resistor.But they did have lots of problems with the switchs those years.Rocky
Like you stated, if high only, most of the time its the resister.
But it could be the switch as well. The resister takes most of the abuse though. But the motor , resister , switch and its connecters all work together and can be effected.
If the motor starts to draw to much current it can overload both the switch and the resister. The weakest link goes first. Typically the resister takes most of the abuse. A lot of times when it goes, it can take out the connecter as well from the heat that occurs, but not always.
If you lose a resister twice in short order, and maybe a switch as well, start looking at the motor. Its next, but for the OP, I'm betting the resister, hope he replies back to what he finds.
