Hello all. I have an old Tac-one that I used for many years for woodsball and last used for the 2012 Oklahoma DDay. It is a stock Tac-one with an X-valve and ULE trigger pull kit. I used it the way I recieved it and have changed nothing. I am dusting it off to throw paint with my teenage kids. I aired it up and it fires correctly but there is a leak at the ULE on/off (as far as I can tell). I have some replacement o-rings and replaced the on/off rings but no difference. I noticed if I fire it and hold the trigger the leak seems to go away. I know I can order o-ring replacement kits which I guess might fix it but because of time it sat on shelf am considering sending it in to get serviced. Just needing some advice from those with more experience. Also if I posted this in the wrong spot don't be too hard on me. Thanks.