I understand that this is the reason the instrument lights are on all the time to give a bit of heat.
Indeed. And I have also heard that the reason for the misting is that MMC picked the cheapest saloon car range from Smiths, instead of the slightly more expensive Smiths-recommended "weatherproof" ones. I have also seen a fix consisting of drilling a tiny hole in the back of the gauge, but haven't tried that personally.
