that the position of the glass is not even to its location on the sag support / quench ring tool. There is too much support along the bottom and very little at the top. There should be not more than 11-12mm band visible around the edge of the glass. The band should appear clear in colour when viewed on the Polariscope light box, with no yellow, red, purple areas at all.
As shown above, sides of the quench ring tool are masking too much along the side edge surfaces of the glass in the spots of high edge stress not allowing enough quench air in.