Snapper 21 inch Push Mower P21500

[poohbear]

I have a 21 inch self propelled push mower Model P21500. I bought it in approximately 1994. Recently it started acting up. It will not stay at any of the drive setting which determine the speed of the self propelled drive. The drive wheel will get pushed completely off the drive pulley. I have inspected it and everything looks like it is in place. The only way I can get it to work properly is to use a pair of vice grips to lock down the connecting rod to the frame. I stopped at the local dealer and asked them if they had seen this before. They had not.

Has anyone experienced this and know of a solution. I would appreciate any help.

Thanks

 

[Snapperfreak]

I'm trying to think of what might cause that. Could u post some pics of the drive system?

 

[poohbear]

Snapperfreak
Attached are some pics. Hope they help.

 

[Snapperfreak]

Ok thanks. If everything down on the deck is in good shape I'm wondering if the lever up where u adjust the speed has an issue. If the vice grips aren't used and the wheel moves off the drive disc I'm assuming the lever up at the controls moved too? Is the lever that adjusts the speed tight up against the bracket? That's all I can think of that might affect the drive system in that way.

 

[poohbear]

Yes, the speed selector handle does move and seems to operate properly. I have not noticed anything unusual with it.

 

[Snapperfreak]

Shoot. Sorry, wish I had another idea.

 

[combatcarl]

Got a straight-down shot of the drive disc and wheel? I'm thinking that your driven disc is not centered fore and aft on the drive disc. Might be the rotation of them is walking the wheel outwards. How much tension is on the drive lever from the spring? Does the handle move easily, or does it take some effort? How much tension on the spring pulling the driven wheel down onto the drive disc?