I have a "Personal Pace" Toro self-propelled lawn mower. When I started it up today, the transmission suddenly stopped working. It is now no longer "self-propelled". Not a tragedy, but my 12-yr old is terribly unhappy having to push, and the steep hill in the backyard is now a dad-only hill. Bummer. Any ideas or suggestions for how to fix, or what the problem is? Thanks, Bill P.S. I'm the least handy person you've ever met, so talk slowly and use small words.