[SteveandTerri]

I had a similar problem back in late 2018. Keystone reimbursed me for the corrective work. Here's a copy of the post I created after the leak as fixed:

The Roof Openings on my 305RL were not cut in the right place. They were crooked and too large. The AC Gasket didn't make full contact around the openings. For the most part, only half of the gasket actually made contact with the surface of the roof. The rest of the gasket surface was located over the roof openings.

The worst location: there was no contact at all between the gasket and the roof surface along a 5-inch section of the Supply Air roof opening. The gasket was located completely over the opening in that area.... As a result, rainwater was able to leak into the roof opening and the duct. Water also got to the closest lag screw that secures the AC Unit to the Roof. The lag screw was only fastened to the 1/2-inch thick Oriented Strand Board: there was no framing below it. Due to the leak, the OSB softened and the screw just pulled straight out. All four of the hold-down lag screws were rusted.

The RV Roof Specialist that I took it to affixed framing to the roof deck/structure to reinforce the openings and make them a bit smaller (so that the gasket would make full contact with the roof surface). He also installed a metal frame with "up-bolts" (the frame is attached to the interior ceiling). The bolts extend up into the AC Unit base frame. The AC Unit is now held down with nuts and bolts - not just lag screws coming down from the top side.