first measure width and height to the back edge of the glazing beads less 10mm each way,if internally beaded easier to take out gasket outside by placing chisel under gasket and pulling out all four pieces,then inside place chisel between bead and frame and pull out removing gaskets makes this easier,usually the beads have fixed gaskets they come out with the bead,when fitting glass make sure the packers at the bottom which the unit sits on are flush with edge off glass if not when you put the beads back the glass will be broke,dont forget to put the gaskets you have taken out back before fitting
malc, November 2008
