How to fix a loose neck?

I finally got my first DD! She's Sakura Miku 2.0 I got second hand. Also thanks everyone who replied to my last post, I did a quick clean with an alcohol wipe and all was fine. I just didn't go over her face out of fear it would smudge off.

Biggest problem now is her head doesn't stay in place. I took her head off to check if there's damage to the neck hole but it looks fine. It's the actual peg that's very wobbly, and whenever I try to reposition Miku's head, it just falls backwards because the wig is so heavy ^^; 

Can I fix this? Thanks

I think you should just be able to tighten a screw on her inside frame where the head peg connects to the body frame. To get to it, you'll just need to remove her head, arms, and pull the chest piece off, which will expose that part of the internal frame.

I'm pretty sure it should be here (or similar):

Unfortunately I'm going to have to disagree. 2.0 Dollfies simply have loose necks, as they have a slit cut out of the back to allow for greater flexibility. I believe there is a way to make the heads less floppy, but it requires the O-rings.

I can take a picture when I get home.

Edited 7 hours ago by Giallo_Gatta

You can Tighten the Screw at the Neck Peg Jointing-Point. you can also either slip several Silicon O-Rings on the Peg to Clamp the Head down

and induce Friction-Based Tightness... or instead Tightly Wrap the Peg with PVC Tape so that the Head may be Firmly Pressed into Place...