I'm borrowing a used toro walk-behind. Started it up today for the first time in 2 or 3 years, so the guy it belongs to tells me. He's willing to help me fix it and show me how to fix the problem the next time it comes up, but I want to be armed with some of my own knowledge before we get to work. I understand it's a pretty common problem. Basically, the right driveshaft/wheel aren't engaging when I put it in gear and the thing just runs in circles. Anyone that could provide some basic instructions on how to fix a faulty snap ring/worn out shaft would be greatly appreciated. Bonus points for pictures!