I just bought a Bunton 48" gear drive walk behind mower that was in the process of an engine swap. I used the belt that was already routed through the deck. With the blades disengaged I can crank the mower and it will run a few seconds then the belt grabs the pulley and the blades start turning. I adjusted the idler pully further away from the blades. I adjusted the little L brackets away from the pulleys a little bit. I then tightened the brake band that stops the blades from turning. When I cranked it they did not turn but I could see smoke from where the engine pulley was rubbing on the belt. My thoughts are that the belt is too small. The mower is well used and Im sure has had many people work on it over the years so anything is possible. I am pretty mechanical but have never worked on a mower like this. I also dont have a manual for it yet. My question is if I have the tensioner adjusted where it is not really pushing in on the belt and the deck still turns, Does it seem like the belt is probably too small? thanks for any input!!