Seal between the cam tower (where the cam is located) and the head that is just above the oil filter. Could be the cause and is easier to replace than the cooler seals.

As Tony suggested, clean the area then inspect. Would also suggest pulling the belt covers to check behind there. Could be coming from the front seal on the cam.

Forgot to mention. Last time I was at IMA a month or so ago they weren't as busy as usual.

Understood, and probably already toast. I'm replacing the sway bushings, but probably ought to fix the leak first!