When I pulled mine out, I left the bolt screwed in several threads and smacked the head with a 3lb sledge. Took I think two and the mirror came flying out. From there, I used a step ladder to rest it on so I could snake the electrical connector out and remove the mirror and arm completely. Cover comes off and the 4 bolts are exposed. On mine, the wood that held the bolts in place was rotted/loose from the inside of the cap. It's far enough up that I couldn't reach them to place them back on or put new ones in. So, I used 3M 5200 to bed the bolts in where the wood was hogged out (in the holes) and then also put a bead under the main bracket. Put it all in and tightened the bolts. After a short curing period, I re-tightened the bolts as best I could.
It still shakes a little bi going down the road, but not nearly as bad and I'm no longer worried about it falling off while driving.
2007 HR Scepter 40 PDQ
400 ISL, ~67K on the clock....for now