Ford KA passdenger side window not working

The passenger window goes down fine but when trying to close the window, it only goes up in stages with you having to push the window back into position for it to go all the way up. Have had runners etc tightened by garage and this worked for a few times but have got same problem. Does this sound like a new window regulator is needed before I purchase one? Garage seems to think so.

Many thanks.