~'76 B15N, recapped n tubed in '15, new beta 15a in '13, home and jamspace use only since '12. I almost never play it without other musicians making noise, but just got my first P bass and have been soaking in the chocolate and I really don't know how long it's been doing this for. It does this on both 8th fret E string and 10th fret D string C's. I wiggled all of the tubes in their sockets a bit (just a few swirls per tube). Could this be solved by some deoxit on the pins and over ten seconds of wiggling per tube, or is this a sign of something on its way out?