The top mounting hole had broken away completely, so I made a 'bridge' from ABS and glued it in place. Once it had hardened, I filled the missing area with 'Milliput' putty, sold in modelling shops.
http://milliput.com/prod.htm This is a type of epoxy putty, which although it worked, took a long time to harden properly (about a week).
I shaped the Milliput to follow the line of the fairing.
I'll smooth this a bit more and respray it.
As an experiment, I tried to prise the patches away from the fairing with a screwdriver, but the plastic would have broken before the patch came away, so it looks strong enough.
To try and avoid the cracking happening again, I made rubber washers out of an old inner tube and fitted these behind metal washers on the nuts and bolts holding the fairing together. Let's hope this works!
Sheet ABS should also be available in model shops, as should epoxy putty, and you should be able to get ABS cement at a hardware store.
As for David's problem with mirrors, there are some folding mirrors on the market:
http://www.ebay.co.uk/itm/270853973629?_trksid=p5197.c0.m619 but these look a bit cheap and nasty. Anyone know of decent quality ones?
Norman