Mine was brand new Roger and it leaked where the pipes were attached to the sandwich plate and where they join the cooler. The threads on it just dont seem very convincing at all.

When I fitted it I span the engine over with no plugs to fill it with oil, then left it a bit to settle in the sump and topped it up as obviously the cooler will need a little oil adding to the total.
Still leaked even after tightening so I took it off and haven't touched it since!