Dirty printed circuit board and/or bulb contact wires not contacting the bulb holders. Remove the instrument panel, all the miniature bulbs and their holders. Clean the circuit board thoroughly, especially where the contacts on the bulb holders touch it. Both the circuit board and the bulb holder contacts should be clean and shiny. Then, with the bulb removed from its holder, measure the resistance of the filament of one of the bulbs, directly across the tiny bulb contact wires (there should be continuity and its DC resistance should be on the order of a few ohms). Next, gently bend the contacts on the bulb holders so they make better contact with the circuit board. With a bulb inserted in its holder but before inserting it in its board, measure the resistance across the contacts in the holder to make sure it is the same as that previously measured across the bulb's contact wires. If not, try a different bulb because maybe that one's contact wires are not contacting the bulb holder correctly. Then insert the bulb holder in the circuit board and measure the resistance again, this time across the circuit board traces, to make sure it is still the same as the resistance measured across the bulb's contact wires. Do this with all the bulbs and they will glow just like new.
