I'll take a stab. I think you've identified the secondaries and their center taps... FWIW, you can either use it or balancing resistors to gnd, and/or float the heaters, but depending on the quality of the transformer one or the other will be better balanced than the other. The hv secondary is the red wires and it's r/y center tap.
The black one is likely one end of the primary, and (here begins conjecture) the yellow and blue are probably taps for 120/240 use or one is a bias tap but that would usually be a red/something. That can be identified with a vom, with the thing just sitting on the bench, just look for continuity and r between taps and make a list- it'll be clear as day. The green wire is probably a faraday shield and to be grounded. The continuity meter will work here. Sometimes you can actually see the green wire's termination, so perhaps some pics of said iron? Also, the way the wires come out may help. I want to again re-iterate this is pure guess, but your vom is a huge help here. Also, you could monkey with a little 12v ac PSU but that's pretty sketchy- but not as sketchy as just using the mains. Just start measuring from tap to tap.