Small Engine Troubleshooting Problems? Ask a Mechanic Now.
Welcome to JUST ANSWER small engines, let me try to help you !! I don't know it all, but maybe together we can get you a satisfactory answer!
Belt can slip with the engine OFF, and the key switch on, and brake locked, pull pto switch on, and see if the belt is tight for the blades and can not be slipped on the pulleys, the belt should be tight with no slippage.