I fixed this. I found a little foam plug inside an old lighter (one of those wind proof jet ones with the little catalyst) and was looking at it under the microscope to see what kind of foam it was, and comparing it to foams I had about. Then I realised I could probably just shove that itself into the soldering iron and now it works. The gas regulator is way more sensitive now though, and the high end of the range is proably way too strong. Didn't take any photos but the foam under the microscope looked like lots of... sheets. Kinda like alot of dried snail mucous. Most of the other foams I had looked more like lots of threads making a 3d honeycomb. I guess the sheets compress better to bleed only a small amount of gas through, where as the honeycombs even compressed still have large gaps between the rods.
One thing I think about alot is the amount of threads I find via Google that go nowhere and have no conclusion. But I guess the conclusion to this, if anyone is unfortunate enough to stumble on it, is to try pilfer a foam plug from a lighter.