Basically the fan is too big for it's housing (or has moved on it's shaft) and is rubbing, which causes it to slow down and reduce the airflow on the heater. This will cause overheating of the heater and trip the thermal switch.
Itallian parts - what more can I say.
The cure is to reduce the width of the fan slightly, clean any lint in the heater (that doesn't help either) and reset the thermal switch (which is on top of the drier unit) just push the end of a paperclip in the small red hole untill it clicks.
Reassemble and there you go - no more probs
Took a carpenter half an hour to do with 4 fairly standard tools.
James Webber
June 2010
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