My NSF one came loose and fell onto the moving wheel, rubbing it right through. So I went to take it off to replace it.
At the bottom it is attached using pathetic plastic screws (why plastic????) they came off all by themselves, hence why it fell down.
But at the top it is held in place by several bolts (through the fuse box) that have NO FLATS ON THE NUTS and they are surrounded by rubber. Which means when you want to remove them - you need to grind them off (they were rusted solid) which is nigh on impossible as they are totally innaccesable.
So to recap - flimsy at the bottom and total overkill at the top.
So the lessons are. Check:
1. all the plastic screws are still there
2. they are all still tight enough
So far its looks like £50 plus a good amount of thumb skin to fix mine.