F07 is a open circuit lower heater element or a failure of your main electronic control board. remove top cover, r/h side panel ( when viewed from the front ) near the base you will find a motor capacitor. cable tied to this is the heater plug. you can check continuity of the heater from there. if o/c change heater. if test is ok buy new machine cos your boards gone
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Try fixfault.com to fix tumble dryers.