ISTR he's got a sash window reconditioning bit on his web-site.
Worth a look maybe, as are the bods at Mighton Products.

Yes, I've got a Mighton catalogue. Just a few questions, as you seem to know
something about it.

Firstly, can brush seal be used for the vertical sealing as well as the
horizontal? They aren't very clear about it.

Secondly, how do you cut the 2mm strip in the non-beaded side of the frame?
Do you have to remove the frame panel?

I'll see if I can find Jacob's website...

Christian.