Use your bubble to the hilt. Level between the tow end plates and the central shaft before sliding the curtain down. Also the u channels / tracks. Glyderol are cheap thin and light curtains that are prone to something called coneing, which is when one side of the curtain starts to travel before the other, doesn't fall correctly and will unravel from its shaft before traveling down the tracks.
This is entirely down to the curtain hanging completely straight and it having completely straight tracks to fall down.
paulandlaura, you seem to know your stuff with Gliderol doors. Could you possibly help with the issue in my thread below, other than get a new door and motor I don't know what else I can do as no one seems to have any idea what the problem could be.