My floor comes out so it was dead easy, you should be able to get at it from the inspection hole though. Pull the unit out (and boy will it make a mess if your tank isnt emptyish)
Meter out between the pins on the wiring gonnector and the tabson the underside of the plate. You may find one of the wires is broken (black had gone on mine)
One tab is unused,m resolder the wire to that tab and then swap the wires on the connector so the broken one and unused one are swapped over.
Before you rip everything to bits check the connectors on the tank and the guage. You should be able to pick up the meter feed and return on the dash.