On Sun, 12 Dec 2004 03:54:43 GMT, Jim vaguely
proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email



I would look into the reason you have too keep "snugging them", and
there's reason to look at the burried nuts. Sounds like a plywood core
that's rotten.

Or maybe a bad design that has a foam core with not even "pads"
between the glass where there are pressure plates.

Backing plates won't help if the center is soft.

Which can apply with foam. Same problem occurs. It's best to have
solid "pads" at pressure points, even with backing plates on top.
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Only worry about the things you can control.

Then you have stuff all to worry about!