I have done this a few time with a friend who owns a repair shop. He uses a heat gun like
http://www.grainger.com/Grainger/WEL...NE5?Pid=search
We did find that the power source was the reason for a lot of the older fats overheating. We got a temp of 115c one day on a power source. So double check to see that the power source isn't going bad.
I replaced the power source with the last reflow on my cecha and it hasn't overheated since.