join the club for bad electrics. I have a 97 astravan and am constantly chasing blown lights. I too had a problem with the glove box light, which I managed to sort by pulling it out, and fiddling with the contacts until the spring action alowed the correct contact for lighting the bulb, now that works.
I've had blown bulbs behind the speedo, which were fixed by some guy who was fitting a stereo for me.
Also currently I have a bult out behind the three heater controls in the centre of the dash, had the guy look once, and now the light does come on, but as soon as the interior warms up it goes off. As far as I am aware, when one bult blows it can cause the other bult to go too due to an imbalance. Also, if you do have to replace any of those bulbs, alway do the lot, even the ones that have not blown, that was they are matched and seem to last better that way
cheer - Paul