Interior Lighting Issue

2001 NB GLS. Above the rear view mirror there is a digital clock and outside temp thermometer. Recently the back lights for these went out. But they're out intermittently. Sometimes it's the clock side, sometimes it's the thermometer side. Tonight both went out, but one side came on later.

Tapping on them seems to have no effect. However closing the door usually does, and bumps in the road can also do it...

Sounds like something may just be loose? Or?..

Does this instrument group just pop off with a screwdriver?

Thanks!!