Hello,
Much to my chagrin, I've discovered that my Grafmatic was fully loaded with film. The sheets are certainly decades old.

Sadly, I discovered when moving the dark slide, so the first sheet was certainly exposed. The rest I moved to a lightproof box.

How do you determine if film in a Grafmatic was previously exposed? I will describe as best I can:

Sheet film were loaded in the clips
Moving the dark slide, the first film was exposed to light
Indicator dot showed red, not sure what that means
The counter showed 4, but there's no guarantee this is accurate based on my fiddling around

Any suggestions? Should I try to develop this or shoot it?

Thanks for your insight!

Assuming the counter had been set to 1 when the grafmatic was loaded, sheets 1-3 are probably ok, at the bottom of the stack. Sheet 4 is fogged, and sheets 5 and 6 may be unexposed or at least only fogged around the edges. The red dot means the dark slide is not over the top sheet and it will be fogged if the grafmatic is removed from the camera. Usually one only cycles the dark slide to the red dot just before shooting, and then immediately cycles the magazine to advance to the next sheet immediately after.

It’s worth developing to see what the camera was used for.