Hi Richard
I have the same problem with my Miele T230C.
I am planning to take the top and back off and vacuum clean all the expected fluff off the insides.  A new thermostat may be needed - cost around £15.00 from the internet.  If a new heating element is needed the cost can be £185.00 or over £200.00 depending on where you source on the internet!
Peter Morris petermorriscpa@gmail.com
                
 Peter Morris
                
 November 2007