I am faced with replacing the transmission in a 22040 proline 21 . I am residential property owner and have gone through several mowers. Thought the proline would last a while. I love the mower but the transmission is $250. Is this failure a fluke or typical? I have had other toro's , and honda. All the drive systems seem to be junk. My last toro ( a non commercial 21 that was the spitting image of the proline ) wore out the small gears and sprags in the wheels, but the transmission lasted. The mower is three years old .Any opinions?