Too bad you didn't find the right info to start with.... On a yota box all you do is turn the input shaft all the way left and lift teh sector shaft out of the box. That allows the worm gear setup to slide right out intact rather by taking it completely apart.
I have put the balls in a couple different ways, you can either pack grease coated balls into the two piece tin return tube then coat the balls in heavy sticky grease and put them in one at a time then thread the center worm into it. Or you can take the tin tube out and feed the bass into the assembly one at a time through one of the return holes.. Thats a tricky way to do it but they both will work.