dash illumination problems

i have a 89 s10 blazer and my gas gauge reads full and half tank event houhg its not either of those and for my gear idicator the light is not working what could be the problem

On shift indicator check bulb.
Is all other dash lights working good?
On Gas gauge find the wire to tank unit and take a old bulb type test light to it and see if bulb comes on dim.
And then see if gas gauge moves.
Also check the ground wire and ground for fuel tank gas gauge wiring and plugin.

yes all other dash lights work just not the gear indicator light ill try the gas thing