It looks like I am missing a bell on the Domino.
My 0-9 Unit has an apparent clapper on the bottom but no bell.
A couple of images online show it (this one from PinballMD which appears to be down right now)
https://th.bing.com/th/id/OIP.5I0i56g4DVmIeTCs9emueAHaNK?pid=Api&rs=1
This video shows one with a bell (at the 8:00 mark)
My picture below....Anyone know what size bell it might be and what it is for?
Mark