As Greg says , check the mains socket . It could be a scenario where the plug has ‘sunk’ into the rear ‘tarmac’ of the appliance and could be being pulled out slightly as the machine heats up and expands . Also , if its been hard-wired , you can have probs with loose electrical connections in the socket where , again , as it heats up due to the power draw of the heater , the connections can become dis-connected which then re-connects as the wires cool down .
Personally , i’ve not heard of a motor cut-out affecting the whole board .