I purchased a 42" Ariens Riding Tractor from Home Depot in May. It is a 20 horsepower model with hydrostatic drive.
My problem started after using it several times mowing the lawn. Suddenly the tractor would not move forward or backward. Upon inspecting the drive belt I found it had jumped off the transmission pulley. I took it to an area Ariens dealer because it was under warranty.
They put the belt back on but found no reason for the failure. After using it again to mow my lawn about 3 times it stopped moving again. I found the problem to be that the belt had come off again. Having been a mechanic for many years this time I decided to see what was wrong myself.
Upon inspection I found that the bolts holding the front of the transmission to a bracket had stripped out, the frame where the axle bolts up was cracked and thr front holes were torn out. A very weak system for mounting a part that has so much torque.
I reinforced the frame with steel and installed bolts that went through the transmission case so they won't strip out again. These were two simple solutions to an obvious weak engineered system.
Review about: Ariens Lawn Tractor.