Our Fu Hwa has a large/long connection buss under/inside the flybridge enclosure, right in front of the steering position. You may have the same; start troubleshooting there. Beats lowering the mast, although corroded connections and/or burned out bulbs are pretty likely.
I made a new mast with all new wiring. Its initial 'failure to thrive' was in the plug that I'd misassembled at the base of the mast. You may have a corroded plug there, too.