Windscreen rubber gasket

[Jag4Ever]

Apologies if I'm using the wrong terminology. Over the last couple of years, the rubber gasket/seal (not sure what the correct term for this part is) that sits between the windscreen glass and the surrounding finisher (the one painted Dorchester Grey) has been shrinking such that it's straight-lining the angle at the top corners of the windscreen.

Does anyone have any experience trying to rectify this? I can't find any replacement rubber gaskets/seals, so I wondered about trying to rejuvenate the rubber. I've seen various videos online where people have submerged rubber parts in a mixture of isopropyl alcohol and wintergreen oil (+/- dimethicone). This apparently replasticises the rubber, bringing softness back to old hardened rubber parts. But I don't know if it will restore length to the shrinking gaskets round the windscreen. I wondered if anyone might have tried anything like this before?

Many thanks
David