The OP is talking about the fabric that is adhered to the inside of the boot so your socks are not in direct contact with the rubber. I go thru a pair about every other year, so I've never rehabbed the inside of the boots. I'm trying a pair Grundens now for a change of pace. They are more of a deck boot than a beach/woods boot. Walking on barnacle encrusted rocks tears up rubber boots pretty darn quick. I run Alpha Burleys for regular hunting and Hoffmans rubber logging boots w/ carbide tipped caulks for the steep slippery stuff.
Actually I was thinking the rubber outside part on the "uppers", not the inside fabric which I thought was all one piece anyway, apologies for any confusion.
That said, these boots are unbelievably good - and comfortable - on slippery mossy rocks such as on beaches in Alaska. As good as it gets. Awesome boot.
They also do great on a deck full of tuna blood and sardine scales off SoCal and Baja, but that's a different story. LOL
If I can get another year or two out of them, I'll do whatever the needful is cuz the old ones ain't coming back!
And yes MM: pre-Chinese is the Xtratuff equivalent of the Pre-64. No doubt. Good synapses my man!