Hey, I've got one.
Maybe one of you who is more mechanically inclined than I am can answer a question.
My self-propelled mower isn't propelling itself. So, online, I've learned several possible reasons. The one I think most likely is that the drive belt has lost its elasticity.
So, here's a video on how to replace those:
Don't worry, you don't have to watch the whole video. Just right around the 3:14 marker.
So, my idea is that, if this was the problem, the belt would look kind of slack, rather than taut. And my mower's belt does look slack.
But . . . when they put the new belt on in the video, it looks slack, too.
I hate to go buy a new belt, and go to all the trouble of replacing it (for that you will have to watch the whole video) and then that doesn't prove to be the problem.
But why is the new belt in the video slack rather than (as I would expect it to be) taut, once it's around both spindles?