Its the big rear light clusters, when I've taken them off to change a bulb, they just won't go back tight, it seems to be the little white plastic clips won't grip properly, anyone know how to deal with this – is it just a cse of fitting new clips or am I missing something? (I don't want to push to hard on the clusters in case I crack them!).

Line the clips up, make sure they're difinatly lined, and then wallop them in with your hand

okay, very many thanks for that, was nervous of hitting too hard, I'll give it another go!

light smear of grease on the clips can help

I had same problems but made sure they were 100% lined up and a wallop with palm of my hand and hay presto back on