Aaah, another theater buff here! I used to run the Simplex XL projectors at a local theater here that was built in 1928. They are still running the Peerless Magnarc's and changeovers. They too, have the shear pins becasue that polyester can S-T-R-E-T-C-H! Luckily, I never experienced a jam. They built projectors much more reliable when they also had to be designed to run with nitrate films!
We also have one of those old Brenograph slide projectors there too!
We also have one of those old Brenograph slide projectors there too!