I picked up my PC 557 this weekend (should have done it through Amazon,
but didn't plan far enough in advance.... sigh)

I also noticed the same thing about sloppy fit. I was able to align my
board edges (mostly) when I had the clamps put on with very light
pressure, and then finished tightening.

So - now I'm curious - what should the biscuit thickness and slot
thickness be? (I'll get out the dial calipers tonight....)

Dan