I wish I knew the correct window style that we have... I guess they
would be called slider windows, one half of the window slides
horizonatally to open. They are very heavy and the track which the
window slides in doesn't allow the window to open very easily.

A neighbor showed me how one of his windows was repaired (they are the
same brand/style of window). It looked like a strip of
composite-graphite or carbon had been placed in the bottom metal track
that the window slides on. Possibly something had also been attached to
the bottom of the half-window as well. It slid amazingly nicely.

This did not look like a particularly difficult fix. Can anyone point
me to products like what I just described?

regards,
-jsb