are any led's lighting up on the mpu / driver board ? if there is then you are getting power

It's safer to check if you have any voltage coming out of the transformer by checking the low voltage a/c into the power supply, if you have power getting to the transformer and the transformer is ok you will get the low voltages into the power supply

the easiest and safest way to check if power is getting to the transformer is to do it with the mains plug unplugged from the power point and make sure the switch under the pinball machine is turned on.
then put your multimeter onto continuity and connect the red and black multimeter wires on the two pins on the plug that are active and neutral (the two angled pins)
if the switch under the machine is on and the multi meter beeps then the circuit will be complete and power will be getting to the transformer when you plug it in.