Hello Adam,
I am pretty sure the belt that is on the plastic pulley ( right hand pulley looking at pic) is on the wrong side of the pulley. This can be confirmed by looking at the pulley, if the pulley does not have a V and the surface where the belt runs is flat, the the back part of the belt(the flat section of the belt) should contact the pulley. If their is still too much slack then the belt is probably too long. Hope this helps. Cheers Keith
