The last picture is what I believe to be the problem. Looks like black roller is tilted and string is wedged.
A quick learner from Memphis, TN says:
March 29, 2016
Sorry width is 1/2". It looks like the black roller pivot pin is broken on one side to me.
Paul from SWISCO responded:
March 31, 2016
Based on what I see in your third picture, your balance is broken and will need to be replaced. Start by looking at our S390-40 channel balance, this may be the part you need.