sablesurfer,
It sounds like you did things properly. Your readings were all low, but consistently low so that means you probably didn't flub a cylinder while measuring.
Although I am not sure this will make a difference, you could try the test again making sure the choke plate was wide open, and the throttle was blocked wide open.
My compression gauge is the screw in type too. It has a quick connect between the hose and the plug adapter...it does spin.
Stuart
