Last year I had the trans out again and took the direct drum apart and it had a rolled inner piston lip seal. I had that fixed, I don't have a piston compressor, at a trans shop and put it back together. It shifted better, but not like it should.
That's an interesting comment, got me thinking. If you are talking about the 'inner seal', the smaller one that goes on the inner hub (2" or so diameter), the lip on that seal is supposed to be facing downward. I can't visualize how that seal could get rolled while installing the piston unless the seal is installed backwards with the lip facing up.