The EM-310 receiver is fitted with an EM-34 tuning 'eye' tube. The EM-34 fitted to this set was long past its 'useability date'. I had depleted my stock of EM34's long ago, and folks want 'silly money' for them these days, even dim ones, and NOS ones can cost well over $100. The set's owner had ordered two 6E5 eye tubes for his own stock, , so I decided to make an adapter that would allow a 6E5 (or 6U5/6G5) tube to be used in the chassis. The EM34 has two shadow angles with different sensitivity, and, as such, has two triode units inside the envelope with different amplification levels as shadow control preamps. Unlike to the EM34, the 6E5 (or the Russian version, the 6E5C - which has a different pinout) has only one shadow angle, which then requires only a single triode (but one shadow in the tube is better than a 'dead fish eye'). Also, the EM34 is an Octal-base tube, whereas the 6E5 is fitted with a 6-pin base.
So, I went trawling in my junk box and found an old 6-pin tube socket (recovered from a scrap chassis), and a brand new Octal plug. I wired these to connect the correct pins on the Octal socket with those on the 6-pin socket, used a short piece of plastic pipe and some epoxy to physically connect the socket and plug together, installed a NOS (tested) 6E5 eye tube and the set is now sporting a lively eye tube once again!