The pleated filter was beyond simply hitting with compressed air. The back pressure was blowing the seals on the gasket. There are turnbuckles holding it tight, and those appear to have loosened as well. I had to uninstall the filter, beat the filter (from the outside), and hit it with compressed air, a few times in a row. I re-installed, and the system is pulling great now, and no leaks around the gasket. The turnbuckle system could be improved a bit, but it works. It just needs to be hit with compressed air more frequently.