Make sure the lemo connector is aligned and seated properly. Try reversing the cables at the junction box. See if the problem jumps to the other channel. Report back.
I wish I had more to offer, but I would check once again to ensure all connections are made to their proper terminals, and are clean and tight. I always use a small amount of conact enhancer, such as Caig's ProGold, and then Mapleshade SilClear. Your problem sounds familiar to me, but I can't quite put my finger on it.
Best of luck,
I have checked continuity from junction box to the cartridge and its fine. I cleaned up all the connectors and RCA plugs on the preamp, the turntable junction box, and the base of the tone arm. I switched the cables on the preamp and only the right channel is working correctly. The left channel is very low and I have to turn up the volume to hear the music. I also switch the cable on the cartridge and only the right channel is working correctly. What next can I look for???
I also thought of the preamp. I switched around the cables on the phono connection on the preamp and found out that both channels are good. The only suspect at this time is the cartridge, I switched the cables and the sound came from one channel. The only left now is to get another cartridge to try out.