You probably have a broken piece of plastic there. The first time I had this happen, I went to the JY and took apart another side mirror and replaced just the plastic piece (really the black mounting part). It's not an exact fit, but you have to know where to look to see that. The second time I just repaired the piece of plastic. By repair, I mean I got a screw the appropriate size and drilled a hole into the remaining plastic piece. So I repaired the mount by substituting a metal piece for the broken plastic.
If I had to do it all over again, I might just by a pair of aftermarket side mirrors in black, and not get them painted.
