there are some rumours that is is water that gets in that causes them to die, personally, i just think its the naff contruction and they get dry soldered joints over age as the actual fusebox is quite flexible and is under a fair amount of stress when it is populated and clipped up where it should go.
just realised i should say, fao lillford, mine is a lux BUT doesn't have air con and doesnt have an electric sunroof or heated seats.