Wondering if anyone here has encountered this problem and might be able to give me some guidance.

Car: 1985 Delta 88.
Right rear turn signal is out. Manual calls for bulb 1157. Bulb goes in, works when seated correctly, BUT, won't remain seated. So as soon I stick the socket back in the lens, the bulb comes loose and stops working again.

Here is the part that has me confused: The bulb has the two little notches to hold it in place in the socket, one near the bottom, one a little higher, but the socket clearly appears to have space for two notches both at the bottom of the bulb. The result being that the notches on the bulb don't line up with the indentations on the socket itself.

Anyone ever experienced this? What am I missing? I swear I've changed bulbs before

 

Have you tried to turn the bulb 180 degrees and reinstall? Are there 2 terminals in the socket or 1? Sometimes the spring loaded contacts that are connected to the wiring get corroded and bind or the springs get corroded and break. You might try spraying some wd40 on the contacts and gently move the wires in and out to free them up.

 

Wasn't 1985 the year 88s had separate amber rear turn signals? If that's the case, I suspect the manual is a misprint and you need a single contact bulb- which would have the bayonets aligned as you describe in the socket, instead of staggered for the dual-filament 1157 bulb.

 

If it turns out to be a single filament, then your looking for an 1156 or an 1156A if it's amber.

 

DING! DING! DING!

We have a winner. Glenn is correct.

 

Bingo! Thanks guys. You were correct, the manual was wrong, it's an 1156!!!!!