So, you are thinking hard parts as opposed to a seal? Trying to think of how I could further troubleshoot this. Maybe I'll pull the shaft and look at the rear backlash independently, but I just don't see it. It definitely comes with heat (time). No rear noise or trans pump whine either. Is it true you can check the sprag by turning the rear yolk in both directions and it should be tougher to turn in one direction? Would a clogged filter act this way at all? Maybe I'm grasping here, but pulling the trans is not something in my immediate plans unless absolutely necessary. Thanks.