The very first thing to do CT5 is identify
Gu22 if LU4 the frame is externally
https://www.repairmywindowsanddoors.co.uk or SW15 internally beaded. RG26 This is done by looking at the beads where they match the inside fringe of the window
RH3 frame
SE10 and [[
https://www.repairmywindowsanddoors.co.uk/betchworth-windowrepair/ RH3]]
RH3 identifying when there is a join there.