The first thing N9 to do is identify if the frame is externally or SG9 internally beaded.
SM6 This is done by looking at the beads
UB5 where they
DA1 match the inside edge
Window repair repairmywindowsanddoors.co.uk of N6 the window frame and [[
https://www.repairmywindowsanddoors.co.uk/wallington-windowrepair/ sm6]] identifying
SM6 EN5 CR0 when there is a join
wd19 there.