[Michael C Henry]

I have a pv diaphram tester.The 3.5 g valve I had in it didn't leakvacum. The 6.5g pv I received with the trick kit doesn't leak vacum .The two old 7.5g pv's that came to me in the carbs leak vacum ,slight but they leak vacum. I didn't have this problem before I removed the old pv's . I'm wondering what to check next.
How do you check a power valve to see if isn't sealing off the gas ?