With the machine disconnected from the mains, it would be worth checking the continuity of the conductors from the transformer to the pins in the lamp holder. (Check from the terminal of the lampholder, not just the pins )
If the lampholder is intact (Springs in the pins not broken ) at the same time, check the secondary of then transformer for continuity.
If this OK, check the primary winding for continuity.
If all is OK so far, check continuity of the power supply leads to the transformer.
HTH
Howard