Sorbothane record weight?

Both Mitchell and Record Doctor make very simple and successful record clamps that really do push down and help flatten the edge.
Nothing new really however that's not really what the OP was asking.
But I have found that the Mitchell clamp requires more of a spindle standing proud of the album than the Record Doctor one does so at just $29.95 from Audio Advisor it might be worth a trial.
Also handily happens to weigh 350g....

Thanks for all of the input.  Unfortunately, It’s not as simple as buying a weight or clamp.  My spindle has a pop up plastic collar around it that drops down when an album is on the platter, leaving only the metal center of spindle above the label.  It is less than half the diameter of a normal spindle, and very short.  Without a record on the platter to hold the collar down, the platter will not turn.  (Cartridge safety feature). The platter and tone arm assembly are suspended from the underside of the plinth by three springs, now 30 something years old, and the recessed platter surface is only barely above flush with the plinth.  A 200 gram LP plus 300 grams and the platter IS flush (I checked) with the plinth as the springs stretch, and the very outer edge of of the album can make contact with the plinth.  That’s why I was looking for and trying to find something light other than the clamps I see to damp vibrations on the vinyl.  I’ll try the sorbothane and let you know if it makes any noticeable difference.  I’m using a SoundSmith SMMC 1 cartridge.

Steve

Mitchell clamp requires more of a spindle standing proud of the album than the Record Doctor one does

Michell actually makes 2 clamps for that reason. One for their own tables and one for Rega with the shorter spindle.

Google "Michael Lim light weight record clamp"...

It's a 45 adapter that can be used as a 58 gram weight (not really a clamp) and it's under $15.

I use a  DIY 150 gram weight on my suspended deck (Thorens) and suspect that going even lighter would be just fine.

DeKay

OP
Now you have described the workings of your table and add into it the fact that the springs have compressed with age a little it makes more sense.

Certainly try the sorbothane and let us know the results.

Has2be, I was not aware that Mitchell made two distinct different clamps, mine is obviously the regular tall spindle variety.
However I am using the Record Doctor one majority of the time now as it is also a decent weight to boot so combines two functions in one and seems to sound a little better on my Garrard.