you're welcome.
There is a ring of 1/4 inch thick foam that goes around the inside edge of the light housing, that applies tension, and holds the lense's locking tabs in place (it's hard to explain without pictures
)
Anyway, on my car's light, this foam piece had deteriorated, and that was why the lense and the trim ring came loose, until the ring finally fell off.
To replace the foam ring, I just made a ring out of a piece of 3/8 x 1/2 adhesive foam weatherstripping from the doors and windows section at Lowes.