can you pm me your email. so may reachn you.I will add-in my 2-cents worth about you getting a schematic for this mic that will probably go over like a lead-balloon here in this thread!!!
Depending upon whether or not you are here in the U.S. or not, you could ship your mic to me and I could "Reverse-Engineer" the insides of your mic and draw up a schematic and create some other documentation for you as well. In my "real job", I have "Reverse-Engineered" PCB's ranging from a 1974 API mixing console and the 1968 ALLISON Research "Gain-Brain's" to PCB's designed in 1979 that were used in fighter jets needed by a defense contractor who lost the schematics of their circuit boards. So, I - think - I might be able to handle a single vacuum-tube microphone "Reverse-Engineer" project.
Here-at-home I have the full-blown CADENCE/OrCAD "PCB Editor" Release 17.4 Schematic & PCB Design software ($3,000+) suite and I could help you out by not only coming up with a schematic, but also re-create the PCB layout, although that probably doesn't need to be done. I also have the SolidWorks Premium 2021 3D Mechanical Design software ($7,000+) that can be used to create the mechanical design of any 3D CAD-models of the mic. And, I mention the pricing of my software - NOT - to brag or anything like that, but to only inform you that I don't work with any of the - FREE - CAD software that is so commonly prevalent on this board. I perform mechanical and PCB designs for aerospace/avionics companies, defense contractors, medical electronics firms, R&D laboratories and others and I need to use the same high-end industry standard CAD-design software as those types of companies use. Just sayin'.....
Audio-wise, I have a ROYER SF-12 Stereo Ribbon Microphone and a stereo-pair of CASCADE "Fat-Head" Ribbon Microphones. Long ago, I once owned a B&O "BM-5" Stereo Ribbon Microphone, so.....as one ribbon-microphone lover/user to another.....I'll help ya out, if ya wanna!!!