I had this sort of problem with the clock. The only free part I have
ever received from any manufacterer was the globe my mob gave me which
fixed the problem. I assume that these bulbs are scattered over the
panel.

For fitting that bulb to the clock I gained detailed guidance from this
group.

My 406 is the only vehicle I have were you can still read the clock
when the vehicle is turned off. But turning on leads to the clock and
all the other symbols brightening up.

I imagine that the same applies to the rest of the panel - some sort of
back lighting.