Terry, they basically set the mode from 'plain bingo' to sectional scoring. They are present on every Magic Screen game and direct the scoring circuits appropriately.

@okorange, I seem to recall this coming up in the not-so-recent past somewhere. Maybe when I was fixing up my Bounty several years ago.

I'll see if I can dig that up. I think Phil H. answered that question for me, but I think looking at the schematic will make that pretty clear to me now. We'll see!

While the sequence unit is physically in the act of resetting, it cuts off power to the search index if the game is not in the act of paying out.

I haven't found the correspondence I was talking about, but from the looks of the schematic, because the sequence unit is only really engaged in sectional scoring, I'd guess it is to handle the difference in physical time between scoring sections vs. straight bingo if you have only a couple of sections exposed (Pos A-D). In other words, the control unit keeps on turnin' if there's no sectional payout. But, then again, normal bingo winners are weighted towards the front of the search disc (in rotation).

That said, it's just a guess. Looking at the schematic, as long as your unit is operating properly, it looks like that could be an optional switch.

Perhaps Bally wanted to make sure that a gummy stepper wouldn't cause undue payout problems?

It would have to be pretty screwed up, though. Bally put a goodly number of blank rivet positions on the search disc to account for this, it appears.

I know, just like me, that that will eventually drive you nuts if you don't fix it.