Digital BW, The Print

So I have this old 1280 that's been working like a charm. I have this
big show coming up Saturday and Sunday that I have to hang tommorow
night and suddenly the printer is giving me what appears to be roller
lines. Not the banding thing from that can be fixed by head cleaning
but something else. Seems like it's worst when I'm printing using
black only. I just printed a small color image that looks fine but the
BO prints are looking bad and 90% of what I'm showing is BW.  Any
ideas or suggestions. Fortunately I have a new 1800 still in a box but
I had planned to trade that in for something bigger. I'd rather not
use it but I have to have everything done by tomorrow evening for hanging.

Any thoughts much appreciated.

Tim p.s. I tried printing the BW images in the full color mode and it
gives it a blueish tint.