[NicknamedBob]

The symptoms are not entirely conclusive, but you could have a damaged socket (for the bulb), or a pinched wire.

You may need a patient technician, unless you can arrange to get lucky.

[Tax-chick]

If Dave, my classic-car friend, knows about electrical stuff, we can offer him beer and make him patient. Otherwise, I’ll settle for a recommendation to an honest and patient technician.