Hi I dont know if this will help by my WD440 displayed flashing:-on/off, Drying high heat, Reduce Creases and time saver lights.
Cleaned out lower filter at rear of drum behind white cover plate which sits between the rubber drum outlet and drain pump and was not really soiled. Still lights flashing
removed pressure switch at back of powder drawer and the clear tube along with the larger white tube near lower filter, found minor debris in white tube. Clear tube ok and no blockage, blew into pressure switch to check function and seemed ok but may have been jammed open circuit prior to me blowing, checked switch function with multimeter and seemed to require a fair blow to get to register closed circuit so adjusted screw on front of switch to reduce required pressure, refitted offending switch and voila all now ok
Mark Gilbert, November 2009