I have just carried out this repair, however I thought I would check the thermistors before buying new ones.
The problem is that the connectors are of the horrible "scotch-lock" type, the wires are pushed into the connector relying on the blades inside to cut through the insulation and make contact. After 10 years these had tarnished, I removed the wires, cleaned the inside of the "blades" cut some of the wire back and refitted them. I then checked the resistance value at room temp, about 3.2K
You could solder and hot-melt to insulate if you prefer, this may be a more permanent solution, certainly better than the original method ;)
After re-assembly everything works as it should and only about 1/2hr labour cost-wise :) Hopefully this may help others ;)
Matt :)
Workshop 15 Ltd, January 2013