Compression seems low . Are you holding the throttle wide open while testing ?
Test the tester on a known good motor to see if the gauge is still good .
You might consider renting a tester from an auto parts store ( loan a tool program ) and seeing if you get a different reading .
The hose isn't going to make a big difference , a pound or two , maybe . Mine only went screwy after the hose got bad enough to not hold air pressure . Removed the hose and back to reading good again . (edited)