I have a used (up) Toro ZTR that I don't know the model number on, but it might not matter for diagnosing this problem. The right stick seems to influence how the left stick performs. For example, if I am stopped and push the left stick all the way forward, the left side won't go forward (it just refuses to move) unless I push the right stick forward just a tad. The right side also goes a little faster than the left. Anybody have an idea of why this is happening?