It could be that one of the jumpers is defective.
There is a way to check this. The EF91/92 jumper for each socket simply connects pin 7 to pin 5. That is, it connects Grid 3 (pin7) to the Plate (pin 5).
To test this, you can easily make this connection in the socket. Put your LD back into EF95 mode. (I am assuming that EF95 has been working fine). Looking down on your sockets, the pinholes are counted counter-clockwise, starting with the pinhole to the right of the gap. Therefore, pinhole 7 is the last pinhole to the left of the gap. Cut two small pieces of 26 (or smaller) gauge stranded wire just long enough to allow one end to be inserted into pinhole 7 and the other into pinhole 5. Strip the ends of the insulation off both ends and then carefully insert these wires into the pinholes in both sockets. Next, carefully insert the tubes. Having done this, you have tied pin 7 to pin 5 in the socket which is exactly what the EF91/92 jumper was designed to do.
If you feel comfortable doing this, I suggest you give it a try and see what happens.