My breakaway mirror broke when I tried to swivel it. I found after removing it from the door that the toothed retainer washer on the turn spindle had popped off. It looks like the mirror and motor base is attached to the inner bracket with ball and socket fasteners. The problem is they don’t want to come apart. Do they come apart for disassembly of the mirror apparatus?
I think you have to replace the entire mirror assembly. It should bolt onto the door - access the bolts/nuts from the inside of the door after removing the cover panel from the inside - it should pop off. Replacement mirrors are widely available over the internet if you don;t want to pay the top price demanded by the Chevy dealer. There is a large after-market for these mirrors - many are now made in China.