You could try cleaning the condensor (see the manual for how to get this out from the bottom of the dryer). However, my mother-in-law's tumble (same model) has the same problem, and cleaning the condensor (which hadn't been done in >1 year) unfortunately didn't sort the problem ! I also found this advice on another site: "Plugged filter, screen, or drain. If you hear the pump running, that is a good sign" Good luck ...
John C, December 2009