As long as you have the proper tools the rebuilding was very simple. The only trouble I had was getting the center (positive) pin seated properly; and also getting the old one out. At first I didn't have a screw driver to fit the positive contact in order to unscrew the connection to the feeding tube, but once I got my lazy-... out of the chair and grabbed the proper sized screw driver it was a cake walk.
At first I was using it with my normal .95 ohm coil, which seemed to hit slightly better (could be placebo effect) but now that I've wrapped a 6-wrap 26 gauge (.60 ohm) coil it is a nice difference. I love the heat it produces and the balance between power/battery life.