If you ever need a babysitter for it... ;-) I guess it wasn't you that sold like 4 of these a few years back? Good job on finding the Altair Computer Club on yahoo, I see a few replies there. If they have a simple memory test loop program or if you can figure out how to write one that would be my first choice of program to run, or you could just do a counting program and watch it and the lights run.
I haven't used one but is there a step vs run? I suppose if something was up with the wiring for that switch you might have a problem only with that button.