RE: Mt 57..... Runs like crap
WOW! Sounds like you've tried just about everything.
If possible, see if the reeds are sitting flat against the reed block. Mine were off a bit on one side due to the screws that hold them on causing some small amount of lift. A few passes over a peice of wet and dry on plate glass and the reeds are sitting flat for a good seal. I sanded the reed block flat. You may be fine, but seems like it would be worth a check.
Good luck.