after a few days soaking, sneak it into the dishwasher while the mrs is out. that will help no end and make life much easier.
report back pls.
also a bottle of water wetter will help keep things nice and stable too when it gets really hot, stops it going way ott

Now I saw Water Wetter and thought it was another glass hammer, tartan paint, skirting board ladder joke and blimey it wasn't. lol

Sure the wife won't mind me using the dishwasher to fix HER bike, if it was my bike on the other hand! Just need to be off work at the same time in order for me to get the radiator off. She uses it to commute rain or shine!

Also, why the radiator is off, give it a little bit of paint. Tape up the fins etc.

I used black spray hammerite.