Issue with Epson 7900.......

I'm having an issue with my Epson 7900 printer, and I don't seem to be able to nail it down. Occassionally, not often, I get black ink spatters on my canvas prints. I may do a run of a dozen or so images, and then for no reason one comes out of the printer with black ink spot in various places. I've tried running several cleaning cycles, but it doesn't seem to have any effect. It's as though the ink is "dripping" on the canvas. Anyone else had anything like this happen?