Hi , I found this info online that may help you. let me know if it doesn't and I will look more.
#1 The return spring for the clutch will run between the bell crank assembly and the tractor chassis.
Looking at the images below from the Sears PartsDirect site, the bell crank is shown as item 48 and the return spring is item 55. The spring is set out to the side in the image to allow a clear view of other parts, but it is still in its relative position, so it will run back from the bell crank. You should see a hole or notch in the tractor chassis that it goes to but it will be a fair ways back on the tractor as the spring is stretched quite far to get the proper tension on it.
If the spring is in place and you are certain no debris or bearing issue is preventing the bell crank from moving freely over its full range, then your spring might be weakening or the belt might be too worn.
Connect the short end of the spring to the hole in the bracket that is welded to the foot pedal arm (brake/clutch pedal). You can tell which hole the spring was in by the worn area around the the hole.
Place the spring so the other end is pointing toward the front of the tractor and find a hole in the frame or a bracket on the frame just beyond the end of the spring with a worn area around the hole. The worn area is from the previous spring being connected to the hole.