I have the same problem with the door roller mechanism - it developed after about 12 months. Some further twelve months later I have not found a solution and have to lift the door manually and slide it. Its rather unsatisfactory!
Difficult to follow this video if you're starting with no knowledge of the product.
Lyronx 1: Hope your 'brain' is as incisive when you're older. Until then your comment is less than useful and you should try to put it to more creative uses.
Unfortunately for me (living in France) Playlist.com is only available for downloads in the USA