Motorcraft FL-910S cut open

Motorcraft FL-910S from a neighbor's Craftsman tractor with a Briggs and Stratton 26hp V-Twin. It was in use for about 70 hours with Rotella T4 15w40. A Fram PH3614 went back on with Mobil Delvac 15w40. Filter looked good, all of the louvers in the center looked open, was too difficult to get a good focused pic of the center core louvers with my phone though.