Having a difficult time changing heads

I just got my 50cm body for my DD head and removing the default 01 head that comes on the obi50 body is giving me a hard time. I've seen a tutorial on how to change the head, (http://blog.livedoor.jp/mimiwoo/archives/51569280.html) but it seems like the neck peg just wont come out. Like its connected to the whole skeleton in the bust or something?

To remove the Obitsu head, grab the head over the top, with your thumb and first finger a little behind and below the ears. Squeeze hard then twist the head back and forth (like it's saying "No") and pull up. The head should come out with the neck piece still in the base of the head. Use your hair dryer to heat the bottom of the head and push the neck piece up into and through the head.

 

Then use the Mimiwoo tutorial. It's the best one I've seen.

Thank you! I actually messed with it for a while yesterday and the body that I have the neck piece connects to the whole bust skeleton, its hard to explain but the whole neck piece was connected to the whole thing and I had to unscrew it completely to get it off. Like in the tutorial you are supposed to unscrew the spring, on my neck piece you can't do it because there are hinges on it. I'll take some pictures but ended up making a neck piece to fit in the DD head with a screw, washer, and a small plastic tube.