Can I fix a Toyota Estima wing mirror that over rotates on starting?

Our 98 Estima's wing mirror got swiped in a car park one day, and since then, the automatic swing of the mirror on start up makes a nasty click where it should stop, but keeps rotating around instead. if you offer a bit of resistance its happy to stop in the right place, but its pretty annoying to be poking your arm out in pouring rain to do so! is there any easy fix? Its a chrome covered mirror, and we've been told theyre very hard to get hold of ..

Mel B
March 2008