I want to update my windows and most of the sashes are in great shape and pretty energy efficient. I just want to make the windows slide up and down like new ones. Some are pretty loose and do not seal because the window doesn't sit in there tight. Also a small board is used to hold the window open. They do not have weights and never have. I wanted to put tracks or slides or something on the existing windows. I can modify the window jambs for extra space but can not find anything besides whole sash replacements. I would really appreciate help finding out a way to update these windows. Thank you, Mark