I have a splt second that does this! Found your post while searching how to fix

I've just encountered the same problem. These were the settings of all DIPs when I first got the Infinite Extra Ball:

1 - off Coin Chute 2
2 - off Coin Chute 2
3 - off Coin Chute 2
4 - off Coin Chute 2
5 - on Bonus Ball
6 - on High Score
7 - off Balls Per Game
8 - off Not Used

9 - off Coin Chute 3
10 - off Coin Chute 3
11 - off Coin Chute 3
12 - off Coin Chute 3
13 - off Add-A-Ball
14 - off Add-A-Ball (Memory)
15 - on High Score Feature
16 - on High Score Feature

17 - on Talking Sound
18 - off Maximum Credit
19 - off Maximum Credit
20 - on Display Credits
21 - on Match
22 - on Extra Ball
23 - on Extra Ball (1 Per ball / 1 Per Game)
24 - on 5 Bank Lites Carry Over

25 - off Coin Chute 1
26 - off Coin Chute 1
27 - off Coin Chute 1
28 - off Coin Chute 1
29 - on Special 2/1 Lit
30 - on Special Feature
31 - on Red Special
32 - on Red Special

I think you were only asking about the Add-A-Ball DIPs, but I'm not the one looking at the code and more information is always better. Here are my results for all combinations of DIPs 13 and 14:

13 Off, 14 Off - Infinite Extra Ball
13 On, 14 Off - Normal
13 Off, 14 On - Infinite Extra Ball
13 On, 14 On - Normal

The results are the same whether DIP 23 is On (1 EB per ball) or Off (1 EB per game), though when the extra ball behaves normally the 1 Per Game setting is respected. I tested switching DIP 31 Off and 32 On to award an extra ball for Special, and you do get the infinite extra ball if DIP 13 is off. Also, code does correctly respect the setting of DIP 22 turning the extra ball off.

Can you tell me what the Add-A-Ball feature is meant to do? I understand the concept in the traditional sense (award additional balls instead of replays, sometimes many per ball in play) and the intent here seems to be to be able to award a maximum of 3 or 5 additional balls, but the manual does not describe these settings beyond that you can turn them on or off.

Makes sense about the Add-A-Ball, it's just not explained in the manual at all. And since this game is being setup for standard Replays I wouldn't have though to look at it at all if it didn't cause the infinite extra ball bug.

I can burn EPROMs, but this Split Second is a client's game in for repair, so it'll be leaving sometime soonish. If you're fixing bugs, though, I *think* I've heard the game make the speech callout for "Mystery Ball" when it would be qualified but the Bonus Ball DIP switch is turned off.