I think what I would do is adhere a wooden block to the top with a strong adhesive and then secure it to the wall and cabinet. I would do the same in the front to secure it to the cabinet and then chalk any gaps around the cabinet not using silicone.
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Retired Navy
Jake my sidekick (yellow Lab) 10/04 - 05/20
2017 RAM 2500 CC 4X4 Cummins Diesel
2016 Flagstaff 26 FKWS
AF&AM & El Korah Shrine of Idaho
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