air dyer purging every 10s

Just looked for the check valve on dryer. Can't find anything. Maybe the style that bolts directly onto the air tank doesnt have it? I pulled the inlet fitting out but nothing there. Still can't find any leaks on the truck. Its just building air to 130 and when it purges it to 125ish it builds up the lost 5lbs and purges again. I rechecked my unloader valve, all orings are in place. 3 are on the unloader: two on the "housing" and one on the top inside lip. Theres one more o ring in the kit but I can't find if it actually goes somewhere else or if its a spare. About to deal with the problem lol

 

Correct. I found the problem. Rebuilt/cleaned the compressor head, and all is good! Thanks for everyone's help!!!