For the last year I've been folding my side mirrors back when parking in my garage to avoid hitting them when I walk past.
Yesterday my passenger side mirror cover cracked as in the photo. When I looked at the drivers side, it is also stress cracking in the same place. So much for good German engineering
It appears that when the housing is folding back there is some component part internally or possibly the rubber seal that is compressing the housing and causing it to crack.
Has anyone else come across this malady?