Cover up the face.

The Cambridge 302 vario needle can fail to zero correctly at power up.
The instrument uses a light source and photo sensor to find the zero
position. If bright light overpowers the light source then the needle
can fail to position properly. Sometimes it goes around in circles for
a while. Power it up with the face covered.

This information is already posted in this newsgroup inside some
threads on similar tipics. As far as I can tell it is not documented
on the CAI web site or in the manuals. I thought it was worth posting
again as its own topic and hope it helps someone.

Mark