Greetings, on my 1987 300sdl, the left low beam is going out intermittently. And that is literally the only light not working, and again it works about half the time. I have high beams on both sides, low beam right side, etc. I changed the pigtail plug and that did not help, and switched bulbs and that did not help. I’ve replaced the fuse for that light and no help. Is the main switch the likely culprit, or the high beam, turn signal switch? Thanks!!