You will probably have to remove the access cover, since on some models the belt straddles the shifter, and well as remove the deck to get better access from underneath, and well as remove the engine pulley. Some people just bend the guides out of the way by the engine pulley, but I don't recommend it, because unless you get them bent back correctly, they will cause future problems. Part of the problem may be just the belts, but I have another question, can you push the rider with the tranny in neutral, I am just trying to rule out a stuck parking brake, which can be a common issue on older mowers.