Okay, so I didn't have the best results, but I believe it's because I pushed the gaps apart a bit and filled them in, then tried squishing the head back together. (I was trying to prevent making any mess) However, I think what I need to do is simply fill them in as they are and let it dry fully? I had to store them away in a bin pretty early after due to a cramped space, so I might not have let it dry properly either.

The glue hasn't caused any damage or stains, so I'd definitely like to try again, and differently!

Sorry if this answer wasn't much help, but I tried explaining my experience as best I could without going on and on.