I have some internal gears for an 8 and 3/4. Anyway I can determine if he could use them? If he can he can have them.Measure the back lash before any disassembly. Then the carrier can be removed repaired, and reinstalled w/o removing the pinion. When reinstalling the carrier return to the original back lash. If you've never done this type of work and don't have the special tools? Do yourself a favor and take to someone who does. This isn't a beginer job. I probably have parts.
Doug