Hi everybody! (I need a Dr. Nick from The Simpsons graphic there)

Just got 3 pachis on craigslist, 2 that were supposedly not working - Popeye and Saint Maria. The Saint Maria was supposed to work with an intermittent ball shooter problem, and the Popeye was supposedly broken. I've gotten them to power up, they pay out just fine when balls are dropped in pockets, the graphics are awesome and work perfectly, but neither shoots balls. I opened the front doors and gave them a cleaning (dust, tape, candy wrappers, Popeye looked like someone may have spilled some soda in the front ball tray), checked the connections for the wires coming out of the ball shooter assembly to the circuit boards on the back (all connected), and checked for loose wires (none).

On the back of Saint Maria, there is a VERY small box at the bottom left that has a lit-up number "7" in it. When the door of it was ajar it said "8", but now it only says "7". I couldn't get a legible picture of it, but there's an index on the back with numbers 1-7 and a string of characters after, which I assume is a list of error or status codes. I tried drawing them out but a few were well complicated and I failed spectacularly. Maybe someone else has one?

What else should I look for? What would be a logical next step? Has anyone had a ball shooter problem with either of these machines?