Just confirming, using a soldering iron does work. It is a bit risky though. Might I also suggest changing the upper arms to red as well, involves removing pins, but well worth it IMO. Here's my version.
Nicely done. I initially wanted to do mine like this but the pin removal put me off (I've done it only a couple of times) so I went with the red shoulders.
Just think there can be an army of Red Alerts out there now, all with subtle differences.