The fastest way to swap diodes may be to do it from the component side, without even removing the circuit board from the enclosure. But for easier access and less difficulty, I’m going to remove the entire printed circuit board (PCB) from the enclosure. Since almost everything is mounted...
I may continue to look for one, though. Anyway, here are the diodes I got: As you can see from the picture, these diodes are type 1N34A, which suffice just fine for a crystal radio. Here's what they look like: You can actually see, if you zoom in really close in the above ...