65 Valiant headlight dimmer turned, gauges go all the way up?

I call instrument specialties to get some tech help on the issue. I asked him if the circuit board could be the issue. He said he doubted it would be in the circuit board. That it seems it's in the wiring. That's all they really told me. I know the cluster is grounded to the frame. Do I just make a ground wire and put it on one of the bolts for the cluster and run it to the dash frame?