My throttle doesn't return back to the correct position. I removed the cover off of the carb and see that theres's two cables, one to turn the throttle (bottom) and one to return things back to their normal position. i assuming that they both work together. But when I turn the throttle, the top cable on the carb has some slack and doen't push in to the cable sheath like it should. Is there an adjustment I can do or are new cables needed. I tried with no luck to lube the cables.