^^^^^^^^ there are 2 1/4" or 7mm screws holding a board to the back of each rear red plastic lamp, the board just has 3 sockets for each bulb, it is a pcb but there's not any active electronics or anything on it.
I had a dead rear signal last week, problem for me was a bunch of melted plastic inside the sockets the bulbs plug into on the circuit board.
all 3 holes on both sides had a bunch of melted plastic but it only caused a problem on the right turn signal.
I don't know where the plastic came from, the sockets themselves are plastic but they're not melted, they just have melted plastic inside them. I used a dental pick looking thing to get it all out.
edit: now I see the bulbs are supposed to have some type of plastic base to them.
http://app.infopia.com/img/image/fp/VPID/4259761/extra/1/size/250
mine don't it must have melted off and that's what the plastic was inside. Interestingly I had to buy a new bulb and it didn't have a plastic base at all, must have learned their lesson about that.