Maintenance head too heavy, help?

From my own experience, usually with bigger dolls though, sometimes if you can just add friction it will help. Friction and tighter tension. On large dolls I use hot glue sueding but on such a tiny one maybe a tiny silicone kip would help.

 

Hot glue in a thin layer or for this one because of how fine/thin it is, a silicone washer might work better.

 

Try what you have glue wise. You're just providing a rough surface for more friction. Worst that happens is the glue doesn't stick and flakes off which would say what you've got won't work.

You could also try gluing the silicone washer on. Not sure what adhesive sticks to both resin and silicone. Maybe a bit of a silicone ear plug between doll and the washer would hold it in place.

The friction based approaches such as this will benefit from tightening the stringing too.

The head opening looks pretty small (hard to tell exactly in the photo though). Seems like you could insert a thick wire into the neck and up through the head. Maybe put a few layers of heat shrink tubing over the wire to get it to the right thickness for the head opening. Or bend the wire back and forth to make it wider, etc.

You could use thicker elastic for the stringing. Or maybe add a second string just from the chest to the head. Use anything you have to anchor the second string in the chest, then pull up through the and add to the already installed s-hook.

Just throwing out some ideas.

 

Low temp, definitely! Hotter glue might damage/soften resin.

 

Low temp for sure.

If the silicone washer is getting 'sucked into' the string area its probably being pushed up by the neck into the head cavity I'm guessing. What I might suggest then is a silicone tube - through the hole and then up the string into the head, causing more friction and then it won't move. It will make the head significantly stiffer. The problem is finding these is a bit harder. You can find 100% silicone tubing in aquarium supplies and sometimes electrical supplies. The dimensions would be whatever the small area around the neck + whatever internal width, and then eventually calculating the circumference. I don't think I explained that well, and it's kinda a pain to wait for such a part, but if for some reason the hot glue fails you, there is another option.