What causes these to go bad? Age. They are held together by one rubber "O" ring that is likely now 30+ years old and brittle. On the left you will see three vintage Joe figures we picked up with a small collection last weekend. The owner had attempted to repair them with the wrong size "O" rings but evidently couldn't figure out how to attach them to the upper body. Notice the size difference between the ones I use in the boxes and the ones he had inserted into the lower body sections.
The first step will be to unscrew the Phillips Head screw located in the hole on the backside of the body. The upper body section will then fall into 5 separate pieces.