Hotpoint tumble dryer heating problem?

I have just replaced both the thermostats and the heating element in my Hotpoint Aquarius condenser dryer, and it worked for a few hours but then the heat cut out again. It will work again if I fix the thermostat, but I can't keep taking the back of the machine off every time it cuts out. Any ideas what else I need to replace and if it is even worth doing? THANK YOU!