[Oilydad]

Presumably you've removed the instrument panel to do this?

There are 4 main bulbs, in holders, for the panel illumination, and about another 12 underneath for the various warning light circuits..Also 3 above which are often overlooked.

(See next post as I can't add a picture now.)

Did you check that the bulbs are sound, and working in the holders BEFORE replacing them in the rear of the panel. Could be a dodgy holder... If they ARE working, have you twisted them round to lock them into place? Personally I'd use ALL NEW bulbs, because whilst you've got it all out, it makes sense to do it as the the capless bulbs are only about 50pence or so each.

Have you reconnected the ribbon cables firmly, and the earth cable?

If you have done all this, then you have a fault with the actual PCB, and it's a question of looking at it very carefully preferably with a magnifying glass or somilar, because you must have a break in the solder somewhere on the circuit that feeds the bulb holder in question.

I'd get all 4 out again, put NEW bulbs in, and then test them in the holders BEFORE replacing them. Sometimes old bulbs look OK, but aren't. To have two working and two not suggests the bulbs to me.