Revrse light issue

So I noticed when I bought the car, only one reverse light worked (pass side). Figured no biggie, the bulb is out. Last week
noticed backing into a spot that I had NO backup lights now

So today I opened up the driver side and took the bulb out (easier side to access - no tire to remove). It was a little black, but didn't look like the filaments were broken. The socket was filled with a yellow goo, is that OE? Anyway as the cornering lights are the same 2057 bulb, I swapped them. Bulb was ok

Had my daughter come out and when I put the car in reverse from park she said it flashed on then went out....same going back into park. WTH? So then I had her watch the pass side while the driver side was out. It went on and stayed on, hooray I have one at least. So I put the bulb back in the drivers side and the pass side still works, but the drivers side only stays lit for less than a second....

Any ideas where to look next? I thought it might be the goo, so I cleaned that all up. I put a little aluminum foil on one side of the bucket to make sure it wasn't a loose contact (it wasn't).
I guess I need to take it apart again and put a meter on it to see if the voltage is momentary...

Also, car has the center shift console mod, but the other side is working now.....


Oh and Roo, I only had to wiggle the lens around to get it out with the help of a screwdriver to push the plastic under the lip of the D pillar. (light got stuck behind the metal, tight fit)

Yes the YELLOW GOO is bulb grease - helps keep moisture out of the socket, helps the longevity of the bulb