Thank you very much for all your help. I did finally work out what was wrong. It was a seal missing on the bolt ( one of the big ones) but how that happened I don't know. At least I learned something new. So happy to get it back working. Thanks again
Yep - if it was working, then you cleaned it, it normally means something you've done yourself has messed it up! Frustrating isn't it!
Simple solution - wipe the paint off the outside and then jut leave the gun in your kit bag! The temptation for paintball players to mess around with their kit is legendary and the risks to cocking something up are very high!