Mine are yellow (it's the lens that's yellow, so yours might just be faded/bleached out).
I don't know about LED's, but on both my 67's, the bulbs in there when I got them were pretty small (the glass part wasn't much bigger around than the metal base). There's another bulb (the bulb/part number escapes me right now, but I can probably look later) that's slightly larger but still fits in the same socket. I switched to those and it made a big difference.
Could also be a bad ground, though. Might want to check into that too.