I'm hanging a mirror on the wall (drywall) that has rigid hangers on the back. I'm using a heavy duty wall anchor and measured but when I drilled, the screw is about an 1/8 of an inch off and the mirror bracket will not slip on to the screwhead. Can I tap the screw/anchor over a small amount so that it fits or do I have to repair the wall and start all over again? The mirror isn't that heavy and weighs less than 10 lbs. (maybe around 7 lbs). The studs don't line up with the wall correctly for centering the mirrors aesthetically, so screwing into the studs wasn't an option.