A friend of mine said his Toro self-propelled front wheel drive lawn mower had been very jerky and now it won't move at all. He took the cover off and the drive belt seemed fine so I offered to take a look. This procedure is very similar to replacing the belt on a rear wheel drive mower as well. See the links below for the parts and tools I used:

Toro 38990 Drive Belt:
https://amzn.to/3Qfd0PJ (affiliate*)

*Purchasing from these Amazon affiliate links earns my channel a small commission. Think of it as a tip that doesn't cost you anything. Thanks for the support!