Creda 48121 ,Trigger Board relay chatters

I had a call to the above double oven dur to the oven making a ‘vibrating’ noise for about 10 to 15 minutes when either oven or grill is switched on.

The noise is coming from the relay on the small pcb mounted in the top of the oven.

I can’t find any problem with the rest of the oven, does anyone know if this is likely to be the PCB at fault of if any other components may be causing it.