71 Swinger dash lights pulsate when turned on

Doesn't look like anything has been messed with as far as I can tell. It's a 45K mile slant six car that was gone through in the early 2000's, beautiful car. I tried replacing the bulb for the turn signal socket I could get to from underneath the dash but that did nothing, still won't light up. Car doesn't have fender indicator's. I just discovered this the other night as I have only driven it a few times since I got it, and never at night.
I would start by making sure the cluster has a good ground to body.
Lack of a solid ground can cause all kinds of whacked out stuff.