Also, push the pedal down and engage the parking brake. Then get off, and get down, and reach up to the trans pulley, and wobble it up and down
and check the slop, the input shaft bearings get worn out on these after while, and they make a kit.
As well, look at that 5th bolt point like ILENGINE pointed out, as that is a good possibility. Also, there for a while, Murray had a big problem with the
metal of the tractor body cracking badly at the area where the transmission bolted on, and causing belt troubles.