There are a few different ways to gain access to a ball diff's
adjusting screw. This is the easiest and fastest way that I've found:
Step one:
Remove the front-right wheel:

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Step two:
Remove the hinge pin that holds the hub carrier in place:

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Step three:
Move the hub carrier out of the way, and remove the red urethane bushing to gain access to the screw:

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Step four:
When you've made your adjustments just follow the steps in reverse order (Don't forget about the bushing!), and you're done:

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Remember, you can only get access to the adjusting screw, you can't remove the differential or regrease it, etc.
This might work for a lot of other cars, I haven't tried it on any other ball differential car.
NOTE:
You screw up, it's your fault. You cannot blame me if you break something.
Cheers.