if your window sash has got a external beading holding the glass in , ease out rubber seal on inside of opener. go outside and push unit back to rebate. hold unit and ease off beading. pack like a brace effect bottom left and top right, depending which way its hanging. usually you use different colour plastic packers to achieve this. until its square.on internal beaded windows u will have to ease of beading with a putty knife coz external rubber is normally tongued into window section . but the packin procedure is the same. silicon packin in place.
MARTIN HIGGINS, January 2008
