Hello MrGray, if you fancy trusting a oomplete stranger and will post to scotland, i will have a look for you gratis,
i own 2 1/2 Logun s16s's (a .177 a .22 and a junker for spares)
I'm off work sick for the long haul and getting desperate for things to fix
just a thought, to see if you have air flow,
remove your bottle and dry fire your s16 then replace the bottle without pulling the bolt back halfway. you should get air coming from barrel.
docP