The E31 MID (multi-information display) has four bulbs for the backlight which provides a gentle wash of red/orange light behind the characters at night. My MID had one bulb that intermittently worked, the picture below shows my problem, where the characters for the temperature can be seen, the display is noticeably darker:



The bulb replacement is pretty easy - first, the bulb part number is 62 111 391 260 and is available from BMW, some do turn up on Ebay as well but use the correct part number.

The MID is held in with clips at the top and the bottom edges - it could possibly be forced out, but removing the radio makes it a lot easier. The standard head-unit is held on by two (very long) Allen bolts, accessed under two flaps:

If you have a Becker unit, you will need the special tools:

Remove the radio and place it on the centre console (use a cloth to protect the surface). Use a plastic tool under the MID to unclip the unit and tilt the unit slightly upwards:

Do the same at the top and the MID can be released from the centre console:

Place the MID face-down on the cloth, the MID has four bulbs on the top, these can be removed by turning anti-clockwise by one-quarter turn:

Once the bulbs have been replaced, fit the radio back in the console first, this allows (especially with the Becker) the loom to be positioned so it does not get squashed - the MID can them be pushed back into place.

All done, time for a cup of tea.