My rim on my 6" headlamp was never fitted to the bike when I had it and I found all the bits in a box. Since having it powder coated, the rim appears to be really tight to the housing,a chrome plated clip at the base of the housing secures it in place once attached.
I'm not sure if I need to clean the powder coat of the lips or tap it with a mallet and cloth?
Julian
Julian the first tip is, don't try to fit the rim with the headlamp shell bolted tightly to the side brackets. slacken the bolts off first, as they can sometimes distort the shell. Otherwise you sometimes have to go round the flange on the shell with a pair of pliers and bend it inwards. Just go round gently and keep trying the rim. Ron