Unlike the parallel valve intake hold down flanges which slide off the tube and can be reworked easily, the angle valve units are married to the tubes for life. Once they start to rattle around in the flange clamps, they keep digging deeper and deeper. The "fix" is to surface the mating flange until the recess is shallow enough to make the intake tube a bit proud. The easiest way to do this is to cut the tube and have the flange surfaced or replaced, but at that point you might as well do the SDS o ring mod and be done with it. Yes, you can slide the flange down the tube and go at it with a file, hoping to keep the surface true, but frankly I can cut and reweld a tube in less time than that would take.