Lib, How frustrating! Call the APQS 800 number and talk to Amy, she'll help you figure it out. It might be the #8 screw or it could be a circuit board or any number odf things. It's hard to diagnose here and I'm sure someone else will chime in, calling APQS is free and you can talk to the experts on these machines, they'll walk you through everything on the phone and get right to the froblem and the fix for it without all the back and forth to the Forum which can take days and just result in more frustration. I see by your other post that you are already a couple of days into this without solving the problem, so I think the 800 number is your best bet!
BTW, you don't have to start another new post, you can come back to this one and use the reply box to continue your thread.
Hope this helps! Hang in there!