Check the plug at the headlight. My harness/plug seems to burn out periodically, like it's a poor ground problem, but I've re-grounded my headlights right at the steel front panel directly behind the lights. My right plug seems to be the one that starts getting dim, then eventually burns out. I get the plugs in packs of 2 at my FLAPS and splice it in and good to go for another 2-3 years. Still haven't been able to hunt down the real problem.

bob
'87 Syncro Westy w/relays for about 6 years