Manual Oil Pressure Gauge Calibration

[Rockyrob]

My manual gauge needle reads half way when not running ( or even connected) and then goes off the dial when running to the point of not being able to see the needle, . Pushing it back to the low stop it just springs back to vertical (half way) Is there a way to calibrate to get it back to read nil at stop ,that way it should read half three quarters running. Or can I take the needle off and reposition it .

Thanks
in advance
Rob