I recently was given a very old Craftsman 6HP with a 20-21" scoop. snowblower. It started on one pull and ran perfectly but in testing I found the auger was slipping.
On further inspection I can see the chain is badly stretched. I could pull it off easily with just my hands.
I proceeded to pull the cover off and when investigating the chain a small rectangular pin about an inch long fell out of the engage/disengage mechanism on the transmission shaft.
I'm guessing it is some kind of shearing pin but for the life of me I cannot figure out where this pin goes?