This job is on my 'to do' list'. It is a total nightmare to do, as the whole dash needs to come out
Sometimes you can get away with it though, as a 'tap' on the system close to the control nobs deteriorates, and by replacing this alone you don't have to replace the whole matrix. At least, that's what I'm hoping for with mine!
If you find it's the tap that has deteriorated, the code for this is: 7754042, and costs a mere £15. On the packaging it's called a '**** Riscaldat'. If the whole matrix needs doing, then it really is grinding of teeth time, totally horrendous.