Just to confirm, my DF53 wasn't going through its cycle - just ran and ran and ran.
Fault was the thermostat.
Remove the front right hand side panel as you look at the front of the machine, and towards the rear of the machine is a circular black component, with a couple of wires attached and a small red button sticking out the top, about the size of a match head.
Pushed this in, didn't need much force, and there was an audible click.
The reset button didn't appear to move much but the 'stat was clearly reset as the machine then worked fine.
Bob
March 2010