I'm working through early games, and doing so by reading schematics. Spot-Lite, Circus, Stars, and Palm Beach (at least) all seem to give random chance at awarding a step on the extra ball unit while searching on each red button coin.
Is this correct?
In some circumstances, it seems to pay to put in your money in the coin-up phase rather than after you've been playing, as you'll also have a chance at the spotted numbers or etc.
Spotted numbers do impact the number of rivets that can award the extra balls, so I guess it's a trade-off.
I'm just curious since I have never played a real game of the above: how frequently does it actually step the extra ball unit when doing your initial coin?