Which game is it?
American slot software still operates like it's 1982, so setchips are required in order to tell the highly-advanced mid-2000s machine how many lines the game normally has, the max bet, the percentage return to player (PRTP) and half a dozen other things which are usually found in the options menu for the rest of the world's machines. Usually there is a cheat sheet with all of the valid options for each game, but they can be hard to find. Maybe in twenty or so years when MK6 is emulated in MAME (or maybe even Flycast, Demul etc. if someone can convince the devs to have a look) I might be able to trial-and-error every game and add the valid options to the source code like I did with the MK5s.
On the upside, American software tends to have better PRTP options than Australian machines, which usually top out at around 93% (high-denomination machines aside e.g. Big Red)
Variation 99 is ~87% (give or take 1%)
Variation 1 is ~90%
Variation 2 is ~92%
Variation 3 is ~94%
Variation 4 is ~97%
Variation 5 is ~82% for Hyperlink games (Cash Express, Jackpot Carnival etc.), if applicable, and is useless without a link controller as the jackpots are stuck at $0