The plan was to replace it with a 1N4007 and a dropping resistor to bring B+ down to the required 130VDC. I was measuring current draw to size the dropper when it popped. I think I got enough information to make an educated decision about what value and size of resistor to use, so it's all good.
The selenium tester was more for amusement value. It just confirmed that the device was indeed dead.
Nice memories spring to mind. I love that "old electronics" smell.