Bizhub c552 will not print yellow above 70%

[skywalkers]

All other colors print fine but if I print a test page of yellow with a value higher than 70% the page comes out blank. Any value under 70% prints out just fine. I have changed toner and imaging unit with no improvements.
Any I ideas?

[Albonline]

i think i remember this as being a print head issue, after trying hv boards.

[skywalkers]

i think i remember this as being a print head issue, after trying hv boards.
Thanks for the help. You was spot on. I had removed the print head a few days ago to clean it because the material on the cleaning wand peeled back and got glue all over the lens. When I put the print head back in I apparently messed up some pins on the cable when putting it back in. I was able to fix the pins and get it back to printing correctly. I never thought about it being the print head because we had printed for several days with no problems but after speaking with everyone here. I found out that all the jobs that had been printed was black and white.
Thanks for pointing me in the right direction.