Where can I get Koss Electrostatic phones repaired

Someone gave me a pair of the original Koss electrostatic headphones, still in the original box but without any documentation. I was given the phones because they don't work and the person reasoned that, being an audiophile, I might be able to fix them myself or know where to get them fixed.

Externally, these phones look like new. They have a very odd connection configuration. I tried connecting them but they produce nothing. I've inspected them superficially and examined the connection box internally. I have not tried to disassemble the phones themselves.

Since I have no previous experience with this type of headphone and no literature, I'm not sure how to proceed. Any suggestions/advice would be appreciated, or if you know of a repair service that has experience with these phones, that would also be helpful. thanks