We have a ricoh aficio 1035 with grey backgrounds. We have done a complete pm, including drum, developer, and main charge. The Mchn is at 250K. Any suggestions on what we could be missing?

Test the voltage from the avr board relating to dev bias. It is quite likely that the voltage isn't dropping resulting in no dev bias. alternatively i would try the transfer roller if it hasnt had one in 250k

Isn't this the one that you have to put a piece of paper between the drum and developer to prevent waste toner from cycling into the DV mix during DV set-up? Did you do this? If not your DV set-up comes out overtoned. Thus leading to grey BG. HtH -Cope