Tuning AF condor check valve leaking

Hey guys, I have a Condor that’s a few years old, started leaking from the check valve. I took it off, but it looks like there is no o ring on this, is that correct? Do I need to just order a new one? I tried cleaning it and all but it’s still leaking. 
Do I need an AF one or can I throw a generic in it? Was thinking about ordering one off Amazon if I can go generic, but wanted to also ask if anyone knows if it’s 1/8 npt or bssp? Assuming it’s 1/8 npt ...