BC,
You're right on. It is a 240(1990). sorry for not including that info.
And you're right the black one was on the righ side(passeenger) and the white one was on the left. Funny thing is its been that way for awhile and has worked ok. It just "suddenly started acting up. Or so it seems.

There is as slight chance that I, absent mindedly, switched sides as I was troubleshooting and trying to solve the problem(senior moments are almost the rule rather than the exeption these days). It could be that the original problem was solved by changing the light bulb, but then i created the other mess. Its possible. All I know is that after all that hassle all I did was change sides with the sockets. Now everything works fine.

Also, iam in total agreement about the relative simplicity of working on a volvo, vs other cars. But you will have to admit that the tailight situation on the 240 could've been disgned a bit better. That said, Ill keep the 240, thank you.

Whats this marque-brand thing? That sounds interesting.

Thanks

Lawrence