I have found a easy way to tighten up wobbly necks/heads of fabuland figs by using clear nailpolish topcoat.
When the heads of your figs are wobbly, the removal of the heads is just a bit more easy, still you have to pull a bitt hard (do it carefully)
Put the nailpolish topcoat on the round joint of the neck (nailpolish topcoat comes with a little brush in its cap)let it dry for like 30 minuten, than put the head back on the fig body.
Move the head around a bitt so the nailpolish topcoat that was on there too much comes lose, you can remove the lose tryed bits of topcoat with a needle or some sort of little pointy tool VERY carefully.
Now you fabuland fig can move there heads again!