ok here is how i made all my gauges work like new. (temp.,gas,clock, oil pressure, volts)
remove the gauge cluster, then remove the lugs that hold each gauge from the back of the housing. i used a small rotary tool with a small wire wheel attached, i then carefully cleaned the two posts of each lug(you will see what i mean once you remove the lugs). also clean any copper surface that the lug comes in contact with, for good measure go ahead and remove the bulbs and wire wheel the contact areas on the circuit board too. i promise once you take the cluster out this will all make sense. while you are at it replace all the 194 bulbs too, add dielectric grease to all electrical connections and also make sure you clean any corrosion from the main harness and where it connects to the gauge cluster.
one final tip, when you remove the small nut that holds the lug on the back of the gauge you may need a small flat screwdriver to gently pry the lug loose