Thanks Dave. I did what you said and gave it a good clean out, and i think it's done the trick. I didn't end up removing the cap on it, it seemed to free up after I cleaned it up. This a picture of it cleaned

[Linked Image from i45.photobucket.com]

I also decided to clean and paint up the cowling
[Linked Image from i45.photobucket.com]

I had some hight temp red paint left over from another job and thought I would give it a go to see what it looks like.