AB Dick 360 Scumming

My AB Dick just started scumming, and I can't get it to stop. I have tried cleaning rollers, and new fountain solution, but I get scumming on the upper right corner (about 1 inch from the side) after about 13 impressions no matter what I do. When I look at the plate, it is not as damp where the scumming is as the rest of the plate. I have been printing for about 9 months, and this is the first time this has happened. I have very little training, so would appreciate any help you can give me.

Thanks in advance.