When i cleaned mine first time i thought there were marks but it was just blackend grease which cleaned off
My springs how ever are still noisy, ive yet to buy the silicon grease, i will have to
Ive noticed though when the lever is on return mid extraction if i push from the right opening to the left, the noise stops, make of that what you will.
I know @DavecUK said there is set length to the threads on the piston, how is this set? Is it by pressure of spring or just by length? Im tempted to try and shock the bolt off as its super tight