i spent about 2 hours trying to get the instrument lights to work today, took the instruments out, cleaned all the bulb holders and contacts up, cleaned fuses, still not working, instruments out again, traced all the printed circuit board and tested it with a meter, still not working.
the i remembered the dimmer thing, gave it a twist and the lights worked!!!
oh how i laughed
(ps. i have a BTEC qualification in vehicle electrics)