Electrical nightmare, 1968 cluster lights, parking lights, horn, etc.

If high beam is faint but high and low beams work, its prob a bad ground from the bulb socket to the circuit board. Ditch the ammeter, and attach the 2 ammeter wires together and shrink wrap. That thing is a fire hazard anyways.

When the turn signal indicator bulbs dimly stay lit when not in operation sometimes thats the sign of a weak ground and power back feeding thru the bulb. Make a good solid external ground wire from the back of the cluster housing to the dash frame. That should help with some of the gremlins.