ugh this Google Group thing is scary, I'll get me a *real* newsgroup reader....

So I am missing the Schrader valve, I don't see it in the hose end where the adapters screw on to, nor in the fitting at the gauge. So it's either inside the gauge or it's just plain lost. I haven't used the thing for eons, it sat on a shelf in the garage but I do remember it working back in the day when I still had most of my hair and better eyesight. I did buy the thing new and used it a few times.

It jumps to 300 lbs on each crank and then drops off again?

No Gunner it goes up to whatever that cylinder's pressure is, the four cylinders varied between 150 and 200 on a 20 yr old engine.

The gauge is missing a check valve in the bottom of the hose above the
spark plug adapter

Bingo, I had everything apart and do not see any check valve or schrader valve.

What's puzzling to me is why you purchased this gauge other than you
were looking to squeeze a penny as hard as possible. :)

Sure I'm trying to save a couple bucks, and also trying to avoid the Chinese crap that is rampant on ebay (and everywhere else). I live in the boonies and don't hit the metropolis very often. And yes, I am a penny pincher on a limited income.

Perhaps Ken can rescue the adapters with check valves off the old gauge. The
fittings are probably standard pipe thread with some Teflon tape.

My compression gauge has a two piece adapter. The adapter for larger spark
plug threads can be unscrewed for the smaller plug sizes. Once this part is
unscrewed, the tire valve type check valve is clearly visible and can be
removed/replaced with a (cheap) special tool.

Paul, I am using the adapters and hose from my old tester with the new gauge in place of the rusty old one. Maybe at some point the check valve fell out when I was switching adapters? Dunno.

Guys, thanks for the replies, I'm gonna sleep on it and maybe look for another gauge on ebay in the morning. BTW the seller was a fabulous guy who offered a full refund including shipping. I searched high and low for the box the gauge came in and told him I couldnt find it, expecting him to refuse the refund. But he answered back don't even bother returning the unit, just use it for a paperweight and then he refunded the full amount. Now there's a nomination for ebay seller of the year