In case it wasn't clear I'm talking about the plastic piece that the seatbelt goes through that is on the ceiling. One of mine broke on one side. I can still use it since the clips are good on one side and use some mild strength glue on the other but how were those things originally put on? I'm guessing when the seat belt was assembled. I took one of the seat belt retractors aparts once in a friends car and it's a pain with that spring in there. Is that the only way to remove/install that plastic piece? If so I'll use the glue method to fix it.

 

That would be the only way, short of cutting and glueing.

 

I had a really badly damaged one and I found a replacement
and simply cut the middle of the back side in a straight line.
I could have glued it after but didn't When its up and in place
you can't even see the crack.