Your outdoor work bench leaves something to be desired.
Do as others have said, clean the inside thoroughly and take the line from hydro to diff. off to make sure you get all debris.
Check the inside of carrier around the spider gears, wash, wash blow,blow.
Then do it some more, those things depend on a surgically clean environment.
Take it apart for a learning experience but that thing operating in the grimy enviro, is trashed!