I've got this problem with all of the colors leaving a void about 0.25" from the right margin on all copies. I don't see anything obvious blocking the laser and have already tried replacing the drum unit.
While toying with the problem yesterday I noticed that each of the mag rollers loses some of it's grip on the toner when manually rolled in the opposite direction that it normally would. This I would expect as the toner is being knocked off the roller when pushed the wrong way but, oddly enough, new toner doesn't stick in this spot afterwards (as it does all the way down the rest of the mag.) The problem also grows worse up to approximately 0.25" from the right edge of the mag even if only a very small area of toner gets 'knocked off.' It continues until the roller is almost bald and does this even when rolled in the correct direction.
I'm thinking this might have something to do with the charging system not putting enough power into each mag to form enough magnetism. This seems much more likely than there being something wrong with each mag roller itself. I've also wondered if maybe the toner carousel isn't level and it's causing the right edge of each mag to rub (though I don't see any marks to indicate this.)
Below is a link to my photos of the mags and the various test patterns from this printer. Any help from a more seasoned copier tech is much appreciated.