My CJ wasn't charging, it turns out the alternator rotor is a common source of the problem. After testing I found my rotor had a short to earth. Replacing it isn't too hard but you need to make a bolt to pull it off the crank. The alternator is under the front cover, 2 screws removes the cover. Remove the wires to the stator and 3 screws attaching it to the motor. Here's the rotor ready to remove, I've already taken out the centre bolt. The outer end of the rotor has a short threaded section for pushing it off the crank. The end of the crank has a tapered spigot that locks the rotor on. Inside the spigot end is threaded. The threads are 10 x 1.5. I cut off a piece of threaded rod about 40mm long and cut a slot in the end to drive with a screwdriver. Screw this through the rotor thread until it passes right though and screws into the threaded piece of the tapered spigot. Here's the threaded rod being screwed in. Once the threaded rod is in place screw a bolt in behind it to push the rotor off. Here's the bolt in place, it's about 50mm long. The rotor should pop off then wind 2 nuts onto the threaded rod, tighten then wind the threaded rod out. Here's the threaded rod in the end of the crank. Now you can install your new rotor!
