At a loss on this one...

244 1987. Didn't have brake lights so I got a "newer" brake light failure relay and that solved the problem...for 3 days.

NOW...only the right rear brake light doesn't function. all of the lights work when the headlight is on, just no brake light.

Not sure WTH to do about this one. Rational thinking would lead me to believe it's the bulb but it's not. And of course rational thinking with volvo brake lights never seems to apply.

I'm thinking that if the running light is working the brake light should work too.

Where to look, what to do ?