[Excaliber]

The power valve tester is nice, but not really needed. The "tester" will tell you precisely at vacuum the PV will open. If it's a 9.5", then it should open at 9.5".

But if you just want to know if it's "blown", simply "suck" on it! Wrap those lips around that gassy bad boy and see if it holds vacuum! If it does, it's working.