I've had a couple of MK VII's recently where the webbing loops that go around metal hoops have started top decay. My original bag was not so bad but the immediate replacement i brought had the webbing loops disintegrate within a very short period of time .. literally weeks.
Once they have gone its unusable really. Given the age of these items 70 odd years .. its little wonder some parts will break down quickly but quite a few of my bags seem to have canvas loops that are already very dry and thin ..
I took a tin of Wax which is actually for re-waxing Barbour jackets and heated the wax up as normal. I then applied it carefully to the canvas loops at either end. i made sure the wax soaked right in while avoiding getting it onto the main bag area. I've found that seems to have helped a lot. Its plumped up the cotton fibres but made them and the stitching a lot stronger (and weatherproof) into the bargain.
Just a tip as genuine bags are the best but clearly some of the materials seem to be aging rather quicker than other parts ...