you will need to take the sash out but not full window,you need to take the 3 or 4 screws out of the hinge that is fixed to the window,take the bottom screws out first but leave centre screw in then take top screws out and again leave center screw in,if its a big sash get someone to hold sash so it dosnt drop then take last 2 screws out starting with bottom,tilt sash so you can get it through window replace with egress then put it back in the way you took it out starting with top screws,hope this helps
shaun www.sdwupvcrepair.co.uk, April 2008