If you can get another sliding window that has a good sliding section, they can be disassembled and then re-assembled with all the good parts in the window you want to use. There aren't any fasteners holding the vertical bars in place - just friction. Carefully tap with a rubber mallet and a piece of wood or plastic. I scored a complete, but weathered RSW from a scrap yard and re-finished it, complete with brush-on clear coat. Looks like new after a year.