Tighten up wing mirrors

[Cowhorns]

The original wing mirrors on my 1979 F4 are always "dropping" I have to readjust them almost every time I drive. Are there any tips or idea how to stiffen them up a bit?
Thanks

 

[Andy McGhee]

If they're like the ones on my F6, I understand the problem!
It's practically impossible to get a screwdriver on them in situ, and anyway, no screwdriver will be big enough - you'll just chew the screw up. A coin in a pair of mole grips will do it - hard without taking the mirror off the door, though.
Good luck!
I