Hi - I've got a problem with one of my upstairs uPVC windows. When I close the window it seals all round except along the bottom corner on the hinged side (rhs). There is a (tapering) 5mm gap along the bottom rail for most of it's width and a similar gap along the rhs vertical rail. It lets in a lot of cold air of course. I've checked the rubber seals and they seem OK.
I've had the windows for about 9 years. Is this problem down to bad installation or just wear & tear?
Any ideas on how to fix it?