Ok to adjust balance to achieve center vocal image?


I have an all analog tube vinyl system and don’t remember having to adjust my balance setting in order to achieve a center vocal image. I do now though. I’m getting a left leaning vocal image with the balance set to zero. Is there a good way to see if this can be fixed so I don’t need to balance adjust to achieve a center vocal image? Could it be a preamp tube going out? Something else? Any harm in just continuing to adjust the balance - meaning am I experiencing any signal loss doing so? 
Thanks! Paul
paulgardner
Tone arm is the stock magnetic bearing one. I’ll check the setup there. 

Hmmmm. I probably just stick to adjusting the balance control if its not an easy fix like a couple have suggested.

Thanks guys!
Post removed 
What about simply tweaking the toe in of the right speaker so it’s in more, or slightly less toe in on the left speaker?
One common mistake with speaker setup is the assumption that everything should be set up symmetrically -- as judged by the eye. But what if there's a wall beside one speaker and a bookshelf beside another? Or a hallway at one reflection point and a window near the other? That will un-balance the sound. The solution is either with treatments or, more simply, to understand the acoustics happening and adjust the speakers so that they match *aurally.* Maybe that's not your issue, but it seemed worth mentioning.
For such a simple tonearm, the Concept/Verify magnetic tonearm can be a bit tricky!

Its vertical tracking force can vary wildly with vertical motion, increasing in pressure/force as the arm is raised. This is why Clearaudio supplied a super low-profile balance beam to be placed directly on the platter when setting VTF.

Any VTF reading taken above the record playing surface will be artificially high. When cueing the tonearm manually by hand, you may be able to notice the weight of the tonearm feels heavier as it's lifted. Also, optimally set up and playing, this tonearm tube really begs to be parallel to the record in order for its flat supporting magnets to be parallel to each other at the fulcrum.

After the turntable is leveled, Anti-Skating is a simple adjustment underneath the tonearm mount consisting of twisting the knob which is the anchor of the tonearm's supporting braided-wire. Typically these are best left at their factory position, usually marked with a black sharpie line and optimized for 2~2.5 gram tracking weights. When viewing the adjustment knob from underneath the tonearm, clockwise increases Anti-Skate, placing more pressure on the right channel outer groove wall & counter-clockwise would be vice versa.