Electrics / Dash Illumination

[Qualia]

I took the S3 for a drive and when it was getting dark and I switched the light on I noticed a problem: Of the three main instruments in the dash (speedo / clock / rev counter), two weren't lit at all and the third was just a pathetic glow, almost non-existent.
Has each instrument got it's own bulb? I fear that it may be a problem with the wiring loom, some sort of shortening, hence the one instrument still glowing very faintly.
I am not expecting anybody to know for sure, but a few pointers as to how to approach this problem would be appreciated. I don't really know where to start....
Thanks

Andy