Fine tuning azimuth


I am finding that I have to fine-tune azimuth quite frequently for stability of recordings in the right and left channels. Even the slightest amount off, and the balance is lost, with individual instruments losing a precision and full volume that they should have. Is it normal for this to be so sensitive and to need re-adjustment fairly often? Also, does the orientation of the grove vary significantly from record to record, resulting in azimuth differing between records? I'm using a VPI TNT/Wheaton Triplanar/Transfiguration Phoenix (the latter with maybe 40 hours use).
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By 'the balance is lost' I mean one side is typically clearer and slightly higher amplitude than the other, and it depends upon on a few degrees of change in the azimuth. It can be either the left or right, with one or the other sounding nearly perfect and the other just slightly off. The central voice is also typically slightly off. It just so happens that today I seem to have found the perfect spot, and it is 'dead on', voice is centered, instruments are appropriately spaced and span completely from left to right. Everything is as perfect as I've heard it. I just hope it stays this way. I managed to achieve this by using the High Fi News and Record Review Test Record's mono cancellation method as a first approximation and then fine-tuning it by ear.
i have a triplanar also, I found it took me a few weeks to nail it by ear, i haven't touched it in over a year...I do use the vta often with every change from 150g, to 180g to 200g....I can hear that...

also do you use your damping trough on your triplanar? if no, take it off, 2 screws, 3 minutes. listen before and after... (hint)
Jfrech said "I haven't touched it in over a year...".
That's good to hear. Hopefully mine will be stable for a while. So far, so good. I also adjust VTA with each record.

I did already remove my damping trough, and I thought it had a positive result as well.