I have a brake light malfunction (intermittant) that's driving me crazy. It's on the RH side of the car (sedan). All other bulbs in the assembly work fine. I have brake light power TO the disconnect on the bottom of the bulb holder. All the bulbs in the assembly ground through a common pin, and all the other bulbs work, so I assume the ground side of the equation is OK. I've scraped the socket clean and even tweaked the center contact and outer ring to assure good contact with the bulb. I've replaced the bulb. I've scraped the pins clean at the disconnect. It's like the thing will work OK when the bulb holder is laying on the trunk floor, but when I tighten it back into the tail light assembly it fails. Does anyone know of a common problem within the bulb holder itself that might cause it to make-and-break circuit?

Also, where is the actual ground lug for the R/H tail light located, so that I don't have to tear half the trunk apart to find it?

Thanks.