ES3500 Deleted YMC colors right after black print

[jltwitch]

Hello, I have a ES3500 that every once and a while the YMC colors are deleted from the image, this only happens in the first print after a black print is done, the 2nd color print and then after will be fine, if you make another black print about 30% of the time the first color print after that black print will not have YMC in it. I took the TBU unit out cleaned it, its making contact fine, the springs dont seem to be getting stuck, the motor that raises and lowers the YMC channels seems to be moving the way it should in 03 mode. Any ideas??

[jltwitch]

wanted to add im doing this in 05 mode going back and forth between 10Fax and 70fax test prints, about 1-4 times out of every 10 going back and forth the colors are deleted.