Lexmark C746dn No Cyan Print

[bmijoe]

Any help would be appreciated. Have a lexmark C746 that refuses to print Cyan. There is are no error indications
Things I have tried:
Replaced Cyan Toner and Drum
Confirmed clear shot for scanner / laser / print head to see drum.
Ran Print head motor test and servo laser test - both = OK
Confirmed high voltage contact continuity from left inside wall to high voltage pcb.
Tried factory rest

Very frustrating

Thanks in advance

Joe