CS 3050ci fading

[xxmandingoxx]

afternoon ladies and gents, i have a 3050ci in the field, in a graphic artist / design office, always full color on average they have over 15% coverage, they print restaurant menus and flyers. Problem is it gets faded not always in the same area (somtimes bands sometimes large circular areas) but its very noticable, i can do developer + drum refresh + calibration + halftone and copies come out good as new for a couple hundred copies then they call and its the same issue, machine only has about 30k copies on it, just trying to figure out my next step!

thanks in advance