Any Home Depot, Lowe's, window dealer, or lumber shop should be able to
give you info you need. Why you would want to keep the weights I don't
know. It's simpler to discard them. Cut the rope on them and remove
the hardware. The'll drop in the well of the window unit. Unscrew the
access near the bottom & remove them. Fill that cavity with
insulation. Go to your hardware store, HD,L's,etc and get replacement
friction guides. They slip into the same space and clip onto the
bottom of the window. Before you re-install the trim, get a load of
that "rope" type black sponge-filled insulation. It comes with self
sticking flanges. Mount it under the guides & behind the window trim.
Make it snug but not tight. Then re-install the window trim.