If anyone is interested in why this conditon exists, here it is.
It depends on where in the AC cycle you last turned the power off.
This can leave the core magnetized.
The next time it is powered up the core presents a very low impedence to the AC input and causes it to draw more than normal current along with charging the filter and pulls on the metal cabinet hard. This amplifies the noise and moves anything that will move and contributes to shortened switch life.
This is why it does not happen every time.
The solution believe it or not is 'soft start' just like an amplifier has.
They are easy to make and install.
A SPST relay with contact rateing of at least 10 amps and a 25 ohm 25 watt resistor wired for a second or less time delay before the full application of AC power to the primary winding, will quiet it down.