to get it out, look at both sides, most windows are externally glazed, meaning the glass is fitted from the outside. first you remove the rubber from the inside, this keeps pressure on the glass and the external beading to stop it being removed. look at the corners of the rubber on the inside, and gently peel one up away from the frame, theyre wedge shaped under the frame. remove the rubber all the way round, and move to the outside. youll now be able to push the glass unit backwards. you may need a small flat blade to remove the bead, start in the center, but, if you push where it was touching the glass, youll notice a gap between the bead and the frame, this is where it comes apart,
!!! remove the top bead LAST!!!
as this stops the unit from falling onto you
youll notice that if its an opening window that opens sideways, there will be packers in opposite corners, this keeps the 'sahsh' square and stops it from jamming, youll need to replace these in the same way, otherwise youre fine to just pack the window for a drainage gap at the bottom
once you have access to the entire unit, you can measure its h x w
another thing to look at though is the edge, most units are 24mm wide, with 4mm glass, 16mm spacer and 4mm glass, youll probably be asked this when ordering a new unit
if you cant get it out, its normally the distance between the bead lines minus 5mm, but, iuf you mess this up, its an expensive mistake as youre left with a glass unit thats too big and the adjustment is too small to re cut the same unit
once you have the new unit, and the old one out, refit the beads (a good punch gets the last one in, bend the corners in and slam the middle with the edge of your hand) then go inside and refit the rubbers, if theyre tight, put some washing up liquid in your hand and run the rubber through it, take your time with this though, DONT slam the rubber in as you can crack the new unit, if it wont go with thumb pressure, pull it out a little and try again
