First, check the gauge! Use a known source of air pressure, like your air compressor, and hook it up directly to the gauge. I've seen compression readings vary as much as 25 pounds by using different testers, just due to gauge calibration. Regardless of the pressure reading, compression pressures should be within 10% or so from cylinder to cylinder.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!