W124 Third Brake Light
 

On my 88 blue coupe, the third brake light keeps falling off of its base, or pedestal. The base appears to be broken and no longer allowing the upper portion to fully snap in. I can't find instructions on how to R&R the base. Has anyone done this? Does it just mean removing the headrests and the parcel tray to find the means of the base's attachment?

You should see two plastic tongues on the lower part of the lamp, they are black in colour and have teeth on them. If you push down on them slightly (they are leaf spring loaded) you can remove the lamp.

Make sure the plastic tongues are there.

Removing the lamp is not the problem, it won't stay on. The "tongues" won't click in any more. I need to replace the base or lower portion.