Five months since you asked but here's an answer anyway. Just had a similar problem with my 4 year old Hotpoint TDC60. I fixed mine by replacing the thermostats. Could your TDC30 have the same problem?
How I replaced the thermostats:
Unplugged the machine.
Thermostats are on the rear of the machine.
To access them I had to unscrew and remove three covers:
First Cover is about 2" square and located on the back, centrally.
Second is just below the first and is actually a piece of angle, horizontal and about 21x1".
Third is the large cover shaped like a moon boot. This piece has a gasket. My 'moon boot' was stuck to the large back panel of the machine. I gently prised the 'moon boot' away with a flat bladed screw driver. On inspection it looked like it was dried dust that had caused the panels to stick together; the gasket was fine.
With the three panels removed, I saw the two thermostats directly above the heating element.
Using a continuity tester I found that one of the thermostats had no continuity.
**Before removing them I took a digital photo to record where the wires and the thermostat with the coloured dot were located**.
I removed the thermostats.
I ordered and bought a pair of new thermostats from my local white goods spares shop for £17. They only come in pairs.
I fitted the new thermostats using my photo for reference.
I chucked the broken thermostat and kept the working, but old, thermostat.
Finally, I replaced the covers and plugged in the machine. It works!
Ulysses_3_1
June 2005