Maybe you could get a rubber seal? In the south island of NZ, there is a shop called E-Hayes that has a massive basement and store with parts that were discontinued even 70 years ago!
You replace the rubber seal that is deteriorated with a silicone seal gasket. They sell kits you can trim to fit your own. What Lewt used was not innovative, its the same as how a deep freezer secures itself.It wouldn't have worked because the seal was torn in certain spots. It would no longer allow the vacuum to form a suction seal in the bag chamber.
U-channel seal gasketOk....for starters, the ONLY alternative machine that MIGHT have a rubber seal that would fit and work is the Holland Electro Toppy. But those aren't commonly seen anymore. And the Lewyt Big Wheel and the Holland Electro Toppy wouldn't have been distributed in Australia or New Zealand. So I highly doubt they would have the part. Something like this pretty much the only alternative is to have something custom made, and that would be costly.

A ReStore would possibly have it, too.