Go to a Camera store. Get a polarized filter. The one I got was about
8in x 8 in plastic and had a cardboard frame it was used to be placed
in front of a light for stage lighting.

I had a circle cut out of it and placed it over the glass display and
taped in place. Sit in the glider and rotate the polarized plastic
until you can see the 302 screen again. Used to do this in a borrowed
DG800. It was slightly darker than ideal, but worked fine.