OK worm the thing is IGT used two or three different ways to set the pay percentages on I Games. ( Different game different set ups ). So if you will pull your MPU out and post the numbers on your Base and Game chips. I have the files for two different I Game Tabasco and if I have a set that matches yours I can put a set in a machine and get back to you on how to change the percentages.
Off the top of my head I will say press the test button on the front of the MPU for three seconds, then on screen bottom left touch Set Up, then touch Machine Options, now you should now see a tab that says something like Game Options, touch that tab and you should now see what percentages that are set. DON"T worry about touching a wrong tab there's not much damage you can do unless your in Key Chip menu, and no where did I say for you to put in a Key Chip.
By the way sooner or later your going to need either a Key 22 or a Key 040 for that Game.