Slow speed slippage
 

I know I've read something about this issue before but I'm not finding it again. My problem is that when I'm turning sharply, at slow speed of course, I experience a distinct jerkiness that feels like something is slipping. It seems to be slowly getting worse. Otherwise, there is no evidence of a drivetrain problem. The car performs fine.

This is a 1996 Legacy wagon. AWD.

Thanks.