Repaired optical encoder wheel but now wont calibrate

My wheel had a split encoder wheel causing the wheel to go out of alignment, so i went inside and fixed using the washer method. Once reassembled and powered on and connected, the wheel starts its calibration for a split second then stops, tries again a moment later and stops.

I'm at a loss as to what it could be, I've made sure that the wheel is free turning and aligned the wheel gear and sliding track to dead centre. I've checked that all the spokes of the encoder wheel are clean and unobstructed, and individually checked the wires on the cable that connects the optical sensor to the main board.

Any other ideas or suggestions would be greatly appreciated.

Cheers

Phil