I have a TDC60 drier with the same promlem and today I fixed it. Take the lid off and mine, there's a PCB in a plastic housing. The soldered joints on the middle relay were dry and if the PCB is tapped the heater flicks off and on. Take the PCB out and resolder all the relay connections and it will work again like mine. DON'T FORGET TO TURN THE POWER OFF - OBVIOUSLY or if in doubt get someone in that can do that sort of stuff.
Nick
June 2008