Glad you're jigged. The way I've seen the dealer fix a case to block leak when under warranty is to remove the case cover and loosen the bolts attaching the case, PS, vac and injection pumps then pry the case back from the block for silicone. It's not the way I'd go about it but it seems to work. Replacing the gasket actually requires as much work as replacing a kdp cracked case. If it's just the cover gasket, piece of cake.
Bill has a point, it could be the vacuum pump or even PS pump. Clean everything well, I like Castrol Super-Clean, and spray it down with aerosol athletes foot powder then drive a short distance. The oil will leave a easy to follow trail in the powder to the leak.