73 Dodge Dart Sport Fuel Gauge Wiring

Red Fish can you give me 2 more answers, please?

1. Could it be possible that a bad voltage regulator can only effect the gas gauge and not the others?

2. I want to take my cluster apart, I've removed it from the dash, however I can't get the wind shield wipers knob off, looks squeezed on. i don't want to break it. The headlight knob just pulled right off?

Any suggestions. Thank you!