Yes, I have done those items you mention, but to no avail. I even purchased a second belt to be sure. Thanks for the reply. It just seems very odd to me. I'm pretty mechanically inclined, but this has me stumped. :( Looks like it is gonna have to go to the mower doc to get fixed.
I've spent many hours trying to replace my belt and get the mower running. It's an Exmark Metro 36 deck belt MGS481CKA36200, serial number 315xxxxxxx, model mower. I've verified the belt is the 82 5/8" x 5/8" V-belt, and if I adjust the clevis bolt one way to get the belt off the keepers/guides...