Sounds like duff contacts in the interlock. You don’t normally hear the buzz as the dryer motor starts up.
Power is across 3+4 when the start button pressed. The door interlock buzzes as the solenoid moves to the latched position and the switch closes (4-5) starting the dryer.
If the interlock switch contacts fail then you can hear the relay buzz while the start button is held in diminishing to a purr over a second or so.
hi just an update on this i fitted the lock the buzzing has stopped but no motor action i tried pushing the drum still no action , so i changed the capacitor and it worked .my thought now is did the capacitor cause the door lock to fail or did the door lock cause the capacitor to fail or was it just coincidence .if i get this again i will try a capacitor first as its much easier to change Thanks John