For sealing, i would use a silicone dielectric grease on the red gasket surfaces and around the cylindrical bushing to keep out dirt and moisture; then some sort of conductive grease on the sliders if it was needed there. Or just a conductive grease for both applications if it is easier to procure just one.
Are the silver traces on the stationary board intact, or have they worn thru? Do the sliders have little spring pads to make contact?
Was your car having issues with gear position that caused you to investigate the sensor?
