If the brake adjuster nut was adjusted and this problem started, I would go back and loosen the brake adjuster to see if it's the problem. Most brake adjusters do not require much to make a difference. Usually one quarter or one half turn is a lot. Good luck!My MTD mower stopped going into higher speeds. It used to go to all 7.
Recently I tightened the brake adjuster nut. Could over tightening it be the problem or should I look elsewhere