Balance control?

Some cartridges are just built like that.  I had a Dynavector XV-1S that had an imbalance - not much I could do except adjust azimuth by twisting the headshell. I hated doing that so I got rid of the cart. If it is the cart (your other carts do not have imbalance issues), you either need a great microscope or get a Fozgometer and test record to determine the extent of the imbalance. You can then decide if you want to live with it or get rid/retrip the cartridge.

While extremes of azimuth adjustment do have an apparent effect on channel balance, the cure is worse than the disease, because the stylus tip will be at a suboptimal angle to the groove resulting in aberrant wear on both the stylus and your LPs and audible distortion as well. I advise against adjusting azimuth to cure channel imbalance.

Lewm and Slaw are correct. Using the placement of a vocalist in the mix is not reliable.
And if your problem is not electronic you could be obsessing over something that could have you chasing your tail for some time, instead of enjoying your records.

Here’s something that happened to me.
After upgrading my turntable table in 2020 I pulled out a test record I had picked up at a used record fair for $1. My main purpose was to check the anti-skating. But a couple of tracks also helped me to evaluate channel balance, which up to that point I thought was just fine. Turns out, it wasn’t, It was skewed noticeably to one side.

Even though my speakers are are equidistant from the side walls and the wall behind them my room layout is asymmetrical. I have CD racks on one side and records on the other and the location of doors, windows, electric outlets together with media storage dictated placement of everything that goes against a wall. I am convinced that this is what caused the sound to tilt a bit to one side.

The test record and the balance control on my preamp helped me to solve the problem. And when I did, it was like… aaaaahh.

Your preamp’s balance control will set you free.
As God and the manufacturer intended.
Peace and long life.

Woof

@woofman74 fair enough. Thanks for the input to you and everyone here. Much appreciated! 

Resurrection of an old thread, but I also run a Herron VTPH-2A phono stage. Keith was kind enough to include gain and trim pots for each channel to help with tube imbalance if this is indeed the case. There can be many causes, as per the posts above, but if you trace it back to the phono stage don't be afraid to try a little trim.