Spot on guys, thanks. Thats the kind of info i like, straight to the technical point with no silly comments like some people leave on here, you've restored my faith in this site.

Took the unit off last night, took it home, changed part, refitted this morning and took it for a nice little drive, all ok. Very easy fix.

There is a postage charge for the part though, and you have to order a min of 5 of the parts. RS are good for electronic components though, i used to use them when i was in electronic engineering, before i turned to cars.