M750 Magenta and Yellow calibration still after numerous reset and many full calibratios

[PaulStCT]

Firmware is upgraded to the most recent 01312023

I've tried resetting the printer numerous times and many full calibration.

I've looked in the service manual and my registration sensor doesn't appear attached the way manual page 135 shows.

I've tried disabling check and the problem stays and does not move with the toner cartridge.

[PaulStCT]

My sensor assembly appears attached to the black flap above where it shows on the service manual and is integrated it the black flap.  It don't see yet how to disassemble it to clean it out and hopefully fix the registration calibration problem.

[PaulStCT]

mine looks like the M775 in this post https://h30434.www3.hp.com/t5/Printer-Ink-Cartridges-Print-Quality/Magenta-and-Yellow-out-of-alignme...

But it looks clean, I did blow it with a air but it looks clean at least from the outside,.

[PaulStCT · Accepted solution]

I took another look and while the registration windows were clean they were not clear and were a little scratched... I took a very very small amount of clear oil on a qtip and cleared the window, full calibration and everything aligned!