you have the little ball sorted,make sure the rod is still in one peice they can break,also check that the adjuster in the side cover can rotate freely,if the cable has the correct free length/travel range it should be easy to set up,,make sure you dont get a 550 cable,,it wont work it has a different free length.,on the 500 just install the cable and have the handlever end fully slack,have the cover end mostly slack,wind the adjuster in the direction so it takes up slack between the ball and tries to disengage the clutch,just let it touch taking up that internal slack,then with the cover end of the cable adjusted a little more,, adjust the handlever end till it feels ok,if the worm threads in the bottom end mechanism are worn it can be difficult to get it to disengage fully,,it loses throw.