Was drilling some very hard steel, 1% carbon, to make a tool holder for the lathe when the belt started to slip because it had heated up due to friction. Tried re-
tensioning the belt then found that the rear cone pulley was rubbing on the belt cover.
Decided to lift the cover to see what was going on and found that the makers, Chinese has inserted a micro switch under the cover , apparently to stop the motor from working when the cover was open.
The drill was being used at slowest speed available which meant that the belt was closest to the base under the cover. The clowns in their wisdom!!!! had brought the electric cable up into the belt chamber in such a manner that the belt was abrading on the cable. At the stage I found it one of the wires had partially abraded through with the potential to have live wires loose in the chamber.
I would recommend that anyone having such drills take a close look in the belt chamber in case yours may be at risk.
My solution is to remove the micro switch and bridge the connections on the main switch assembly.