2x RFT Gefell UM70 / MV692

I'm selling a pair (2x) of Microtech Gefell UM70 / MV629 microphones. These are rare vintage large-diaphragm condenser microphones - multi pattern microphones. 

They work fine, except that one of them has a problem which I believe is the XLR output. Usually the problem has been that the sound might fall out if I use them horizontally without making sure that the XLR-cable doesn't push the XLR-input down (bending the input). When I've made sure that the cable isn't bending the input I haven't had a problem with this one. I believe it's due to the modification on the input - read more about this below - because the input on these are usually modified to use XLR + 48V.

Here are some excerpts from various other sources. I cannot verify that all this is correct, but it seems so:  

Gefell's M7 capsule -- the same capsule used in Neumann's no-longer-made but highly sought after U47 -- gives these mics its smooth natural sound. Unlike the modern UMT70S (which also employs an M7 capsule) the UM70 with MV 692 body (sometimes called the impedance converter or mic amp) includes a transformer which gives it that certain mojo the modern ones don't have.
--- Copied from another Reverb.com item.