The connector between the neck and the head is probably the worst engineered piece in a WM Doll. No matter if you doll is brand new or old, the head might "shake" a little. By little, we mean 1 - 2 mm, but some people still notice it. One option to overcome is to screw the head really tight to the body - the problem with this is that sometimes the head then wouldn't be centered.
To overcome this problem in new and used dolls the easiest way is to use paper tape in order to make the cylinder a little wider. By doing this the heads stops shaking and you don't need to "force" it anymore in order to be stable. Follow the instructions in this tutorial to fix your head.
If you have any questions, just contact us or write us a comment.