the record clamp system on my HW-19 Mk III (presses on the label area only) has been a part of my record playing ritual without giving it any thought.
Yesterday I had the opportunity to play a truly warped record, which I thought would be unplayable.
So, exprimenting with different amounts of tightening I got a truly impressive flattening of the record's perimeter! Good enough for one remaining 1/8"warp after careful tightening (not too much, and not too little). If one tightens too much, the warp can be exacerbated.
The record was played with NO hint of audible warp, in a very succesful playback episode!
It was an unexpected success! Great to be able to report this. I had thought this clamp system would flatten only very mild warps! So, now I have an entire 3-LP opera to listen to, which I had not even tried before. Great little success!