is it a door window or a quarter window? likely the prob is either your regulator, a roller, or something is not lined up right. open it up (remove door or quarter panel)and study the scene for awhile and you will figure out exactly how it all works. you should be able to see what is missing or broken. btw, if while cranking, something gets stuck, never force it or you can easily destroy your regulator and they are expensive. the rollers disintegrate with time, so get a set and replace 'em all while yer at it. dont forget to grease up the rollers and/or channels and that window will be a crankin smoothly.
[color:blue]'65 wimbledon white original coupe I6
'99 silver convertible V6