How tight do you tighten the rear bulkhead, you know the two plastic pieces that hold the ring & pinion, and differential?
I just rebuilt mine (new bulkheads), and set my ryobi cordless driver to 1, and tightened the 6 screws until the driver's clutch engaged. Likely a fraction of an inch pound. Most screw heads just barely made contact with the bulkhead, one was even 1 turn above the bulkhead.
Turned the pinion shaft and there was considerable resistance. Right side output drive wouldn't even turn. Loosened each screw about 1/4 turn and much smoother. Nothing wobbles nor can be moved in a direction not intended.
Is it just the plastic is a little on the tight end of the tolerance, and needs some break in? I'm thinking of running a pack thru it and checking again, perhaps tighten 1/16 of a turn at a time.