What we got here is a Garelli Monza GT with a broken pedal shaft sprocket, the larger internal sprocket that connects the pedal shaft to the transmission.
Exploded.
When I initially bought this it ran fine but had a weird knock to the pedal shaft. It was alarming at first but never seemed to get worse (seller had an explanation for it). Upon inspection there was dark dust and metal debris in the transmission oil and cases. I cleaned the internals and replaced the affected bearings and seals. When the pedals finally got mounted it was revealed that metal was rubbing on metal internally and it needed taken apart again...
