^^Generally^^ about gauges................
Read and heed this excellent thread:
Printed circuit pins repair
In no particular order:
1...Check and repair the harness connector pins for looseness and corrosion
2....On clusters with a plug -in instrument limiter, solder bridges across the terminal connections as shown in the thread
3...Replace the instrument regulator--I realize in your case you have the gas gauge mounted IVR but there are ways to bypass that if necessary
4...Consider replacing the gauge stud nuts with "real" nuts, and tighten/ loosen/ tighten them several times to scrub the board clean
5...Clean around the lighting sockets with eraser, etc
6...Install a pigtail grounding wire to a ground point on the cluster and bolt it to something like the column support under the dash
