[ricard]

So the reason this happens is simply that the gap for whatever reason opens enough for the spring to be pressed out? Would this simply be the result of the grub screws holding the outer parts of the clutch in place loosening?

I'm impressed by the mechanical design of these machines. With the clutches, and one solenoid for the pinch roller and two more under the reel tables, one gets a completely relay operated machine with a single motor.

The larger TK819 etc machines have two electrically selected speeds and a direct drive synchronous motor. Also quite impressive for this class of machine. I suspect though that they were rather expensive in their day.