Attaching comms equipment to helmets..whats the trick?

Hi....I've been having problems attaching headsets to the helmets of military figures.  I was sort of successful with one but only after hours of work.

Now I am working on the guy in the photo below and just can't get those black circular fittings into the grooves on the side of the helmet and pretty much ruined the helmet that came with the figure and had to buy a new one off eBay.

What's the trick for that ? I tried heating both the circular fittings on the headset and the attachment points on the helmet but they just aren't locking into place.

thanks

Yeah, some of those rails (whether on a rifle or helmet) can be a real pain. It just takes patience and a lot of effort. I’ve tried sliding things on (like rifle scopes), but generally what I find works is tilting the piece to go on, get one side in the rail track and push down fairly hard to get the other side to snap in. Be sure to have it where you want it placed when you start. But fair warning, you also have to be careful not to break anything from too much force— see the conundrum there: use force but not too much (the dicking around with these military figures is why I don’t have many — it was a pain in the ass enough to put all that crap together in real life, doing it on a tiny figure… yeah. I’m out).