Demister X Type

[RonAdam]

Hi, I have a problem with the demister on a 2006 x type, sometimes it works and sometimes it doesn't. If I switch to demist and it's going to work I hear the flap close (or is it open?) If it's not going to work I hear nothing , switching off and back on will sometimes get it working as will switching from demist to feet and back again, I'm sure I've seen detailed instructions on how to fix this problem but can't now find it now when I've the time to spare. Is it likely to be just lubrication it needs or some sort of repair?

Thanks in advance