3100cn toner change, now roller marks on prints.

I have a 3100cn, with now 5200 prints on it. The black cart started to give out a while ago, but being cheap, I pushed it as far as it would go - and eventually the prints went completely to garbage, and a clear liquid was on the last printout. The C, M, Y, carts were all still very full, so I changed out the black.

Now there are four or five distinct "voids" of toner on the printouts. I printed out four test sheets, and the marks are coming from all the colors but not the black. So I guess my question is this: did I screw up my imager or something? Or did I mess up my color carts by letting the black go so far?

Is there any way to "clean" the CMY?

Will buying new toner for the color even fix my problem?