This is not specific enough. Is the mic working at all? Did you let it warm up some before testing it? Does it come with a power supply? Is the tube socketed? If so, you could try changing the tube. You can still change the tube if it is not socketed, but it will be more work to desolder the old tube and solder in a new one. Why did the wires get cut? Where do the wires originate from in the circuit? You may have to trace the circuit, if no schematics are available. More pictures of the circuit could help, as well.