Send the meter back to Gossen for servicing then you'll have a meter (and an impressive calibration chart) that works with no doubts, and it won't cost much either unless the innards need to be replaced. There is no sensible way to draw conclusions in a comparison between a digicam and a lightmeter without knowing exactly what is going on to make each reading, and that is unlikely to happen with the digicam.
I just went to check the Gossen website for servicing details to add to this post, and found that non-digital meters are no longer being serviced! This is relatively recent as my Lunasix was calibrated by them about two years ago. Unfortunately the OP will have to compare his meter to some clever light-source in a third-party repair-shop and then hope no parts need replacing.
Last edited by MartinP; 10-28-2012 at 12:10 PM. Click to view previous post history.