Can any gas appliance engineers advise me on a fix for my 8 year old Hotpoint HUG61 main oven fault? I suspect that it is the rotary control microswitch and thermostat, it had become a bit stiff and now cuts out at mark 5-6 and comes on again 1-4 and 7-8. It sometimes trips the MCB also. A new switch is about £65. How much labour will it be to fit this?