Pete E. wrote:

Max-Pro Rubber Rejuvenator... it will not make the surface of the rubber any softer. ...

Your mileage may vary?

I've been using Blow-Off rubber rejuvenator for many years, which I'm sure is the exact same product as Max, and I have confirmed with a durometer that it will actually soften the rubber up to 4 points. It can take many applications, but it has always worked for me. It won't soften a rock-hard platen enough to obtain an ideal hardness, but enough that it can be safely used with a backing sheet (or two). I've never had a platen recovered; there are a few machines that have split or otherwise unrecoverable platens, but they're not worth the cost of rubber replacement.

Rubber rejuvenator is a very toxic chemical to use, so I only apply it outside, and never spray it directly onto a platen as it will damage other surfaces.