For what it is worth:
I was working on an EZ today for false out of ink errors today. I pulled the drum shell off enough to get to the guts of the thing, and found an inch of crud on the front ink blocking plate.
So if you are having a problem with print density on the edges of prints, you might want to check for that.
I've got an ink sensor board on order for the false out of ink error. If that doesn't work, the mount for the ink bottle chip reader will be next.