Air Arms Owners Club

Hi all.
I have a problem with my S200. When the trigger is pulled, the bolt, which is kept in position by the loading bolt screw (item 18 in the parts catalogue) nestling in the short arm of the bolt guide slot, or should be, unlocks itself. This results in air leakage.
I have stripped the bolt and all is in order, the ball and spring that holds the bolt in position when locked closed does exactly that.
To get the bolt to unlock during firing, the bolt has to rotate so the loading bolt screw is moved to the guide slot, the only forces I can see that would do that is the returning cranked arm (item 51) hitting the loading bolt screw. If that was the case then I would expect it to be a common fault which doesn't seem to be the case.
Any ideas anyone?

I am a bit tripsy tonight .... will give it some thought and get back to you tomorrow ...

Raj...Any more thoughts?

Maybe I can describe this a bit better.
When air discharges the pellet, it also forces the bolt back until the loading bolt screw hits the side of the slot in the body. Whilst doing this, for some reason the bolt is rotating, sometimes far enough for the loading bolt screw to get into the long slot and the bolt gets pushed out of the barrel, hence leaking air. In theory there isn't a mechanism for the bolt to rotate in this manner but it is..!!!

Anyone recognise the fault?

PM sent ... Just call me when you have a few minutes and the rifle in front of you.