here is something i learned while restoring my 1974 QT16. transaxle seemed sluggish while driving. i thought my hydraulic pump/motor was dying. turned out to be the bull gear inside the transaxle was badly worn. this shows up as backlash in the drive wheel. i jacked up the transaxle to see if it was binding. i had about a 1/4 turn in backlash.i opened up the transaxle and found the center of the gear was worn out. i now have a good fix for this.