I could never make the Arkanoid spinner I had work with an Opti-PAC or mouse hack. The person who I got the spinner from told me it was just pulled from a working game and should have worked. The transistors tested out okay, so I don't know? I just pulled off the Arkanoid optic board and put one of my own on it.
It worked extremely well for Arkanoid in MAME once I put one of my optic boards on it and connected it to an Opti-PAC. The gear ratio on the Arkanoid spinner gives it the equivalent to a 480-tooth encoder wheel, so it had extremely fast action. But it's still really only suited towards the breakout style games. Playing Tempest with it sucked, to say the least.
What I didn't like about the Arkanoid spinner is the cheap bearing and sloppy feel. The cheap, brass sleeve bearing is so bad that it caused the gears not to mesh properly, thus giving it a very grindy sound and feel. I rebuilt the spinner with a bronze bearing and put a different shaft on it, and then it was much better.