If it turns with no load it's not The cable you may have a rudder needing grease but it's not the back
Cable. Depending on the prop rotation it's suppose to be tight to one side. It's the prop wash phrasing against the rudder and as I said before it's there to help keep your boat tracking straight. I have heard you can file a edge of the rudder to make it easier to turn but I'm not sure which side to do.