First thing I would do is check the backlash of the gears. O don’t have the spec handy, but there should be a small amount of movement of each gear before it contacts, and moves, the other gear. When doing this, you should be able to determine if the pinion bearings are stiff, or if it’s the diff carrier bearings (making the ring gear hard to turn). Or maybe there’s zero backlash causing the tightness. After these initial checks you should be able to determine where the problem lies. Either way it may require a disassembly/ reassembly to correct the setup.