I previously posted this on the E-Class site but got no response. Maybe somebody here can help me with my W210 question.

One of the bulbs lighting my rear license plate on my 1999 E300 is out and I want to replace it. Actually I have no choice since a message about a defecting light bulb takes over the electronic display on the dashboard. I easily removed the plastic cover that houses the two lights but the lights with their own plastic covers are actually attached to the trunk lid as shown in the attached picture. I got the one with the dud bulb (it's the one on the right or passenger side) somewhat loose but something keeps it from pulling out. Don't want to break anything. Any suggestions on getting it out?