A long time ago I came across a ball lock PSI guage that attached to the co2 in side of a keg that was supposed to monitor the pressure. Has anyone seen these for sale lately? I first saw them on williamsbrewing.com but can't find them now...never did see them on midwest or northern. I'm trying to track down leaks and don't want to drain my tank...again. I'm switching all my worm drive clamps to crimp-ons, too.