We have one of your 12" stainless steel Buchner funnel filter. We had a problem with the filter support plate deforming and pushing out of the groove that holds it. The pressure differential across the filter was less than 25 psi. Do you have any idea why it failed? We have two rings with the ~1/4" round holes, but not the open cross that is shown in some of your photos. (USA Lab Stainless Steel 6" in. Buchner Funnel SS 304)