Rally dash oil pressure gauge issue.

I homed the gray wire from the sender to the round printed circuit connector. It was 0.8 then I cleaned the female side of the bulkhead connector Ingot the ohm reading down to 0.5 on the 200 ohm scale which is the lowest my meter goes. That seems "Ok" to me as it's still 0 ohms or more specifically 1 half ohm. Are these gauges serviceable? Should I go into the dash and pull the gauge? Is there a way to test the guage?