Looking at all the doll fun I've decided to keep some of my tonner ladies. So I am going to put heads on articulated bodies. Do I use the hair dryer on high ( how long?) to remove the head ? Do I heat up the head and new body at same time to attach to new body? Do I heat all around or is just the back of kneck okay? Do I use a knife to pry the head off? Thank you in advance.