A Canon inkjet printer, where the cartridge/printhead was jammed.

Cause of this particular problem was that the printhead cleaning module wasn’t moving out of the way (receding into the printer), and was fouling on the printhead.
Many repair shops won’t even attempt to repair inkjet printers because the cost of repair could easily out-weight the cost of a new printer, but I thought I’d at least give it a go (and if I wasn’t successful then I wouldn’t charge the customer)

First thing to try was to wash the printhead cleaning module, as it had a LOT of dried ink on and around it. This freed-up the movement slightly and you could push the cleaning module with your fingertips, but it wasn’t being moved by the printer. Something else is wrong…

These two cogs drive the printhead cleaning sled in and out, and these can be disassembled for closer inspection.

The two cogs are driven by coil springs which are wrapped around the axle, allowing some degree of slip (like a clutch) when things go wrong. We can see that one ONE of the springs, the tang which engages with the gear wheel has been broken off

The solution is to bend the end of the spring to form a new tang, taking care not to stress the metal which might cause it to fail again in service

Printer reassembled and tested, £20 charged which included collection and delivery just a 5-minute walk away from me