Last year when I found a crack on my engine mount, Van's had me contact:
Experimental Aircraft Metal Fabrication Inc.
693 Curtis Hill Rd.
Chehalis, WA 98532
Curtis Airport (Seattle Sectional) Identifier 0WA2
He is the person who now makes the engine mounts for Van's. Since no two mounts are exactly the same, he made a jig from my old mount and then welded up a new one in the custom jig.
The replacement mount fit perfectly.
The reason he didn't just weld up my original mount was that it would "move" when heat was applied and he was afraid it wouldn't fit when I got it back. Also, because of the location of the crack, it would be more work to cut out the bad tube and reweld everything than making a new one.
I would try the one in Switzerland first. The custom mount cost $2,000 plus shipping.