Dave,

Not sure whether this is the problem but flying in sunny southern
Aridzona I learned to put my hand over the face of the instrument
while powering it up and holding it there for a few seconds. This
keeps the sun from confusing the sensors that center the needle.

Don't hesitate to call the factory if you need further assistance,
I've found them to be very helpful. Contact info at their web page
(FAQs too).

http://www.cambridge-aero.com/

-ted/2NO