It's fixed! After removing the tank from the bowl I found the porcelain was cracked. It looks to be a manufacturing problem. In speaking with an AM STD dealer , the hole in the back of the bowl section is used to hang it for drying in the manufacturing phase. It was drilled to far in and the factory tried to silicone it inside, but did not do a very good job, thus the leak. I repaired it w/A&B epoxy putty for swimming pools.