What voltage is marked on the power supply caps?
Here is a copy of the Sunn Coliseum power supply.
I am seeing +50 & -50 Vdc on the schematic.
The transformer is center tapped to give two identical Vac into a full bridge rectifier.
If you read 36Vac that would be bumped up to +-50Vdc after the rectifier.
So maybe the transformer is not bad.