Andrew Gabriel wrote:
In article ,
Steven Briggs writes:
By taking the unit out, you may also be able to spot where the seal has
failed, generally a patch losses adhesion with the glass, and this is
often visible. Reseal with silicone.

One common cause of failure is the drainage channels in the
frame being blocked, so the sealed unit ends up sitting in
a puddle of water along its bottom edge. Check that if you
take the sealed unit out.

But they ARE waterproff you know.

BTW that Norman Wisdom poster is a bit of a comedian. I'd put him with
IMM and Derby' crew.

You can drill the mastic and drain the Silica Gel, Heat the gel in an
oven and then reload it. Seal with mastic again and save up for a new
glass as has been suggested. Whilst the unit is out of the frame
measure it (in millimeters) to order the replacement.

They usually last 7 to 10 years or more.and tend to fail only when
smacked or strained. A prolonged effect of being in a wind swirl might
have one particular window failing more often than others but suspect
it has been badly fitted first.

The glazing needs stiff rubber pads as support in the frame, also the
pads act as wedging to keep the window square (opening sashes for
example, have the pads on the bottom hinge side and on the side
opposite the top hinge.)

If silicon has been used on the pane it will stick to the glass
chemically, so beware its overuse there.