Help appreciated

I have a CANON ISENSYS 728 cd that needs auto grad calibration and Colour Registration running due to colour misregistration
When I try to run autograd either quick adjust or full adjust it says it has failed even before the print has printed out to scan it back in.
It doesnt even try to print it as soon as I press to print it out it says calibration failed.
If I try to run the colour mismatch cycle it does run but fails.
Transfer bellt and sensors ok
I have had this issue on a mid range Canon machine once before a few year back but cant remember what the solution is.