Technics 1200G VTA Lock or unlock is the question?

Someone else perhaps on Vinyl Asylum recently suggested that the locking mechanism, because of the way it intercalates with the threads on the vertical shaft, causes a slight change in VTA when engaged.  Could your observation be due to something like that?  Otherwise, can you think of an hypothesis to explain your observation?

There's an interesting article in the current Stereophile by Art Dudley about tightening things and deformation of structures etc. Of course, overtightening has always been anathema with mechanical reproduction systems. 

 I locked it again and it sounds fine.  It did seem to have some benefits in some ways though, maybe for some circumstances.

Wha....?Your opening statement was based on one trial?Which is it that seemed "to have some benefits in some ways"?  Locking or not locking?

@lewm +1

Given the precision of manufacture of the device it could be more of a resonance issue with the tonearm(?)
Try strong (sustained) female vocal notes and see how the arm tracks/behaves.

Actually, upon reading back through the responses, I thought LewM was going to conclude by saying that AZIMUTH may be affected (which is a distinct possibility) but rather he refers to VTA.

VTA, I suspect, is unlikely to be noticeable because I doubt the locking mech could inflict a change of sufficient magnitude.
Now azimuth on the other hand...different story...

it's a typical audiophilia 

Audiophilia Nervosa is the term.
Yes the issue might affect both VTA and azimuth.

Okay,  I had a moment. 

Haven't we all?