I feel a little silly having to ask this

How does one remove a rear indicator from a trad?
I found one of mine hanging by wire on Saturday. I could see that the two plastic stumps with threaded metal inserts inside the housing had broken. I took the lens off no problem and could get the bulb itself out, but although the chrome ring was no longer secured to the housing I couldn't work out how to remove it completely. I can see that the bulb holder goes into a rubber sleeve - does it just pull out from there? I didn't want to pull to hard for fear of breaking it further. And there's another (earth) wire that seems to be riveted to the back of the chrome/metal piece - how am I supposed to disconnect that?
I've put it back together with some longer self-tapping screws so it will be okay for a while but I figure I ought to look to replacing the housing at some time in the future so it might be useful if I could remove the chrome/metal bulb holder from the (plastic?) housing.
Thanks in advance for your help.