We have received this report yesterday and had forwarded it to the factory for their advice. They have commented that it is likely that the flange has deformed and became slightly oval in shape which causes the PCD to not match the silo flange. This deformation in the filter flange shape can be rectified by using some jack inside the body flange of the filter. And during installation of the filter onto the silo, area where flanges dimensions are correct can be bolted first. The other bolt holes can be bolted by using jack or hole bar to rectify.