I am not able from here to see, smell, and hear what you do or what the machine does. Therefore please be as detailed as you can be. Also, how long have you been using this machine.
Blodgell has about 6 versions of this oven.We need to know what accessories it has like pulse control, Digital control, dual power blower, Integrated control, Blogett IQ, Pulse plus, Inttelahold, Inttellarack, INFINITE WITH PULSE PLUS, and TRIPLE SETPOINT THERMOSTAT are a few of the names we look for. Each relates to a different wiring diagram.
Are you certain that the contactor is buzzing, not the cook time buzzer. Depending on mode switch. With the cook only model in time mode they use a timer for all cooking. When the timer ends, the buzzer runs the cook light goes out and the contactor goes open.
Is the axial fan for cooling the controller running? As long as the power switch is on, it should be.