Well, early this year another seal from my old MF2 system valve started leaking. Tried to find me an replacement seal, but first no luck.
But, not far from my place, here in Holland, about 20 kms, there is an company which makes all kind off seals.
I ordered multiple sizes o-rings and one fitted perfectly. So, now my old MF2 is going strong again.
I know that almost nobody is reading this forum, but eventhough I think it is wise to share this info in case somebody would like to keep his WI system alive.
The company is: Technirub.
The site is Dutch, but google translate is your friend :-)
https://www.technirub.nl/