ah yes this is what the `sonic clean man` has said,adding that commpressed air still may not clear it,this is what i used,thats why he reconmends the sonic clean with a 3hr soak....i like to do all the work on my bikes myself so i know exactly whats been done and what needs to be done,this will be the first time in 10yr ownership that its been fettled by someone else....ive known him for several years and know he will do a good job with back-up afterwards if i need it...ill let you know how i get on.............