when I got my GTV it had a damaged and hanging off O/S door mirror..the seller had thoughtfully provided a replacement but in vela blue, where as the car is verde tropic met..
it was the internal mechanism that had broken on impact leaving both the base and the housing intact.
noticing the mirror bases were corroded I elected to remove both and re-spray them whilst also spraying the ''new mirror'' the correct colour..
when rubbing down and masking the mirror I noticed 4 screws behind it one in each corner of the assembly that the mirror is secured to , I began to think that if I can remove the internals and swap it would save me a lot of rubbing ,priming and spraying....
if you tilt the mirror to its diagonally opposed point to the screw you are trying to remove you can get to them with a thin long phillips head screwdriver..I would advise some penetrating fluid first on each screw using the tube that comes with, the screws will then come out with a bit of beefing
after all four are removed the whole mirror outer casing comes apart revealing the internals (motor and heater element if you have) putting back together is a reversal of the procedure with the caveat that a good magnetized driver will be required as its a bit tricky locating them whilst manipulating the mirror into the correct position.
attached some pics of the housing apart with the screw holes clearly visible...
now I'm pretty sure this has been done before but i couldn't find a how to anywhere despite searching high and low!
this is a very easy solution to a broken mirror which allows you to use any colour Donor provided you housing is still intact, the mirror tapes onto the the rear of the motor assembly so even of this is broken as well you can remove with a solvent and re-apply with some 3M tape.
both bases are now clear of corrosion, primed and ready for top coat!
hope this helps some of you in the future...