I had a bit of a worrying moment recently as the mileometer display disappeared , i eventually found out that all that was wrong was the two bulbs that backlight the display had blown .
I suppose it's not surprising as these are lit all the time the car is running whereas the others only come on now and again .
There are two types of bulbs , simply 24 orange [ jlm1928 ] and 8 white [ jlm1929 ] , orange ones are still available from jdht at around a fiver , the white ones you will have to hunt for as they are out of stock .
To get to them you must remove the drivers under dash liner, undo the instrument pack housing screws , i think there's four then you can re position the instrument housing to get to the back and remove the two large electrical connectors that plug in the back .
They are quite firmly held in so i didn't bother unplugging them , i managed to unclip the plastic clips at each end which allow the back of the panel to hinge open enough to 'feel' with my fingers where these two bulbs are and with a small quarter of a turn they will come out .
There's no wires or plugs on these bulbs they make contact with a printed circuit when inserted and turned .
The white ones illuminate the dial gauges , all the orange ones are the warning lights and the mileometer LED display