Just out of curiousity, what version of mame used those options? I don't reconize them. AdvanceMame?
For current mame, there are a few options you want to look at:
-joystick_deadzone
-joystick_saturation
-joystick_map (maybe)
-joystick_deadzone is like your low_margins options, I think. Mame doesn't send the game anything if the joystick value is less than the set number. The default, 0.3 (aka 30%), is really high for any analog game, so you'd want to set it to something like 0-0.05, propably
-joystick_saturation is like your high_margins options, I think. This value sets where mame "tops off" the analog signal. IOW, when the analog stick sends mame value at or above the set value, mame sends the game its max value. The default, 0.85 (aka 85%), is pretty good for analog sticks with circular restrictors, IMO. You might want to increase it for your twisty grip yoke.
More info on these two are in mame's docs folder, in the config.txt file.
-joystick_map is for translating analog values to game's digital (8-way/4-way) signals. A lot more info on this is also in mame's docs folder in the config.txt file. (I can go more into this once you've read the info on this option in that file if you have questions on it; I'm not going to repost the ~50 lines on this one option that you might not even want to use.

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