@PM490: well, that the damage in the examples I posted is only on one side is probably just a random occurance. There are various ways to destroy a sprocket. In every Super-8 projector I have seen and dismantled, there are at least two sprocket rollers with nice teeths which grind into the film should anything happen during projection. Than there is the claw which advances the film frame by frame - it usually makes contact on only one side of the sprocket (it is smaller than the default sprocket size). However, in most projectors, these claws are mounted on rather long beams and the mechanical force exercised on the sprocket is therefore rather limited. In addition, sound projectors have rather long and winding film paths below the projection area which feature nasty stuff for destroying the film as well.
Actually, that analysis shifted me away from using an old projector as basis for a film scanner. These machines can destroy fragile material in seconds.
My stock of Super-8 material is rather limited - it is made up of my own Super-8 movies plus several commercial advertizing reals of the late seventies and two movies I sourced from Ebay for experiments. That’s only a small sample (some hours of footage at most), but broken sprockets are actually very rare. Also, while I was afraid of substantial color shifts with these about 40 year old material, such a thing is actually not so frequent as well. Actually only a few non-Kodak reals I bought in the beginning of the eighties in the US do show noticable color shifts as well as shrinkage and warping.
So, to set the record straight, here’s a nice example of a sprocket where the damage is on the other side of the sprocket: