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.
Balance control?
I’m running an analog exclusive rig and feel like I’ve been dealing with a channel imbalance for awhile now. I’ve tried trouble shooting this every single way I can think of. The cartridge is set up correctly, checked tubes, etc. My question is: am I obsessing over finding the root cause or should I just cave and use the balance control on my integrated? I feel like it would be ideal to find the cause and not use the balance control. Dose using the balance control introduce anything into the signal? Ugh.