How to fix broken mirrors

Beat Mirrors are supported by a casting which can be broken if they are hit too hard leaving the mirror wobbly. If pushed forward too far the outer casing can break near the inside end as well.
This is what you do. Remove the mirror (remember one bolt is accessed through the inner door after removing the trim.) Slide a bit of cornflakes box between the glass and outer case to protect the latter and gently warm the plastic edging the glass with a hot air gun or hairdryer. Ease the glass out with plastic tools or fingernails. Unscrew the glass carrier and remove. Undo the screws holding the rim of the casing and remove. Undo the screws holding the main casing to the casting and remove. Clean everything thoroughly. Take a piece of thin RIGID plastic (I used part of a PET drink bottle) and wrap it round the spring using tape to secure. The cylinder should cover the full length of the spring and protrude about 6 mm above it. With the pivot in the folded position re attach the broken bit with 90 second araldite and hold until set, if the main case needs repair use the same stuff. The repairs will be delicate so handle carefully. Allow to harden fully. Trial fit the main plastic case (which my be fiddly) to see how much clearance is available.
Make sure everything is ready before starting the next stage as you can't stop part way through. Cover the outside ( the bit that would face the front of the car) of the casting and the spring with P40 glassfibre reinforced filler, refit the main plastic case and pack the gap between them with P40. Spread more P40 over the remainder of the spring. Try not to obstruct the mounting points for the rim and avoid P40 emerging from the bottom around the pivot or getting into the top of the spring. The object of the excercise is to encase the spring and the inner end of the casting in a solid lump of P40 the plastic cylinder around the spring prevents it from being clogged up.
Leave a few hours to fully harden after which you should be able to open the mirror in the usual way.
Remove surplus P40 and replace the rim. Replace the glass carrier.Make sure the screw will be clear of the glass but do not overtighten or you won't be able to adjust the mirror. Make sure the P40 doesn't foul the glass carrier when adjusting then if all is well refit the glass after heating the edge of the carrier. Don't forget the cardboard to protect the rim and use only plastic tools or fingernails. I found this the most difficult part of the job. Refit the mirror which should be good as new.