Turntable Right Channel Dropping Out; Grounding Cartridge Body Brings It Back

@dover Thanks for responding. I’ll Ohm out the wires later today. Watched a video on YouTube this morning by The Turntable Man, it’s no big thing to Ohm out from existing cartridge to cable’s phono stage termination. 
 

[Note: I accidentally deleted an earlier post on the same topic.]

@dover I remembered that I had Ohmmed out the tonearm cables when I re-wired the tonearm; but I did it again and moved the arm while doing so. Everything seemed fine, no hiccups.
 

I also investigated the grounding scheme again and found that (1) there was no ground wire on the power plug, (2) the control elements were grounded to the chassis proper, but (3), the tonearm was grounded by three conductors all linked to the 100 Ohm resistor ‘lifting’ the ground available to the cartridge. I had wired the interconnect’s ground wire to the center terminal of a single pole, double throw, switch. This allowed me to select between the chassis or the ‘lifted’ ground when connecting the interconnect’s grounding wire to the chassis of the phono stage. I realized that the turntable was designed to use the ‘signal’ ground, and that the switch was defeating the purpose of the design.
 

Then I had a think.

I considered adding a jumper inside the body to replicate the grounding of I was doing with my stylus brush trick, but by anchoring one, or both, negative signals from the cartridge, I was defeating the Common Mode Rejection feature of the balanced interconnect. I needed to face facts. I don’t know why the balanced connections don’t work, but they just don’t. 
 

So I ripped out the switch and went back with the original unbalanced RCA cables. I have played five (5) sides of three records without any of the issues I described above.

@lewm Thanks again for jerking me out of my reverie and getting my mind back into troubleshooting mode. When I’m working on my own stuff, I forget everything I learned working on other people’s stuff ‘at work’, if you know what I mean. 

@oldrooney 

Great that you have found a solution.

The interesting thing with TT grounds is that with most vintage turntables the TT chassis ground is connected to the tonearm ground and taken to phono grounding post.

Now my view is if you are running a single ended phono stage then in theory any noise picked up by the tonearm/chassis ground is fed into the phono signal path.

I prefer to keep TT/tonearm grounds out of the signal path and ground directly to mains rather than into the phono stage ( assuming single ended ).

The only issue becomes when either tonearm manufacturers, eg Rega, insist on using one of the signal grounds for the TT ground, which means you can't separate them, or the cartridge has an earth strap between the tonearm/headshell and earth pin on one of the channels, in which case you can't separate the signal ground from the TT ground.

I suspect your problem is likely caused by an earth strap between the cartridge body and one of the earth pins on the cartridge - this would mean effectively you cannot separate the signal earth from the chassis/tonearm earth and when you feed into a balance phono effectively you are tying the ground to signal, net result probably not good.

If you ran a moving coil cartridge, I suspect you would not have any issues running single ended or balanced.

I am guessing that if you remove the cartridge earth strap, with moving magnet cartridges, if they are unshielded they are more susceptible to picking up emf - eg the famous grado hum when the cartridge moved across the record towards the tt motor.