I found a site,on the net, in a central state which makes a conversion
kit for old wooden double hung sash. It looked like a great product for
anyone in preservation and wanted the ease of tilting windows inside to
clean. I'd appreciate any help relocating the site. All I'm finding is replacement
window kits. I also remember watching a segment of TOH, many years ago,
somewhere in New England someone had a business where they
would come to your house and redo the old sash enabling it to tilt in. Always
thought that was a clever idea.