The new ones are pretty easy to rebuild. To pop chimney off, put the chimney down a 7mm deepwell socket and give it a few taps with something that's about 1/8, 9/64-ish and a hammer, leatherman or whatever is handy. Once your chimney is off use your favorite precision philips screwdriver and place the point in the lower juice hole and use the lip of the coilhead to gently apply some pressure up. Now, grab a small flat-head and work your way around to pop the cover off. Boom, now you have a disassembled coil head. Rebuild however you like. Lately, I've been digging on 1/16 ID, 30 gauge, 1.6 ohm. Thinking about seeing how much I can drill out of the center pin for more airflow. It's already hogged out pretty well from Kanger.