Canon Pro-100 mystery spring

[conlanthompson]

I was inspecting what appeared to be a paper jam in my canon Pro-100 and noticed this small spring trapped in the paper guides. The printer no longer seems to print from the rear tray and some research indicates it might be a return spring for a paper registration sensor, any idea how I could reinstall it in the correct location?

 

[GoogleGangs]

Yes — that small spring is very likely the return spring for the rear tray paper registration sensor. If it came loose, the printer may not detect paper from the rear feed correctly. Short answer: Reinstall it on the small black sensor lever near the rear paper path, with one end hooked to the lever and the other to the nearby plastic anchor point so the lever springs back to its home position. A close-up photo of the area would help identify the exact mounting points on the Canon PIXMA Pro-100 .

 

[donaldolsen]

I was inspecting what appeared to be a paper jam in my canon Pro-100 and noticed this small spring trapped in the paper guides. The printer no longer seems to print from the rear tray and some research indicates it might be a return spring for a paper registration sensor, any idea how I could reinstall it in the correct location?

Yeah, that looks a lot like a torsion spring from a paper sensor or guide. If it's not feeding from the rear tray anymore, that was probably the reason. I would not try to force it and find a service manual or teardown video of that particular model to show you where it goes.