I had a little look behind the card today. It is an LED, there seemed to be some confusion as to whether it was a bulb or LED. The part number is 4B0919063A.
There doesn't seem to be a "plug and play" upgrade available, so I'll probably leave it as is. The benefit of cutting wires, soldering, finding a suitable replacement, messing about with resistors, etc isn't worth the hassle for having a slightly brighter glow.