In my vacuum rejuvenation project, brake servo check valve fell in half. Can't get part cos Christmas/NY in Australia is complete shutdown - Jag repairers and suppliers probably all on stress/mental health leave at the beach!!! The valves are pricey too.
Diaphragm looked Ok, so used silicon to carefully glue the diaphragm back to each side of the housing, small hammer to bend the tabs a bit.. Put in vice to hold until set but did vice too tight and one side crushed.
Bugger . So made a tube semicircle to fit over the broken bit (hole), epoxied then painted.
​​​​​​It sucks and blows like it should and I have saved over $100.
Please tell me if my posts are boring but they may help someone else in despair!!!!

 

Looks better than the original on my car! If the diaphragm doesn't hold, there are inexpensive plastic ones that can be put in the vacuum line from the engine.

 

...and this is why you're buttoning the thing back up, while other (less resourceful) folks are sitting around complaining.

Well done. Like all "MacGyvers", there's the "get you homes" and the keepers, and I say leave it in.

 

So far so good!! A bit of thinking and fiddling around with $4 of expoxy saves $120. That suits me!!

 

Series 3 XJ (1980-1987) have a similar twin-port check valve threaded to the charcoal canister, Only difference it is black plastic.

 

I well remember these little valves when I was rebuilding my Mark 2 in the 80s ! They are made of Mazak, (USA=Zamak), a zinc-based alloy. Their position on the reservac tank means they don't last long unless plastered with antirust wax. Also the reservac tank also rusts out. I replaced both items on my rebuild, but sold it not long after completion.