THERE IS NO 'GUILTY PARTY' FFS!
A gallery plug is for life, not just for Christmas. It isn't like a water jacket core plug that can corrode. It goes in and is there for the next 50 years, just like the ones in a 1953 30HP motor I am working on today.
It is probable that the case has developed a crack, in which case the supplier will need to change it.
If it turns out to be the cam plug, then the case will need to be split and the plug replaced.
Its this 'blame culture attitude' that has taken this forum from helpful and constructive to mean and bloody minded. Are VEGE dealing with your problem? YES! Are they bearing the sole responsibility for an old part failing? YES! Now you've got this old fart paling!
As these vehicles get older, there will be more problems arising from old castings. They crack, they wear, they die. Components get less and less reliable.
Loads of people have had problems with flywheel seals (not just me) We've tried every kind available including genuine (which just turns out to be the one Elring supply in their kits) Add whatever it is for a new flywheel to the price of an engine and it may go away.
Genuine rocker covers dried up for a while so people had to use what was available. Main bearings went out of production for the early engines for 2 years so people had to buy and supply late cases. One of the premier gasket suppliers sent out a load of faulty head rubber seals meaning that the robbing "bar-steward" enginbe suppliers had to change a load under warranty with no compensation.
Hows about... Thank you VEGE for being honourable.
Have a nice Vanfest... I'm staying at home in case you decide to get pissed and lynch someone.

Laurie Pettitt-Engines.
07824514205