Difference between JMW 12.5 and JMW 12.6 tonearm

I have spoken with Harry before. He is great to deal with and is a wealth of information. Their hours that they take calls are limited and I just thought that someone on Audiogon would know the difference between the 2 arms.

I'd like to bring up an issue with regards to what I've observed with a friend's 12.6.He recently moved to this arm(on a new TNT/metal composite platter)after about ten years with the "fabulous" Air Tangent!I have observed,if looking at the arm from straight ahead(as though one was checking azimuth),that there is a constant "tick tocking",or left/right(twisting) movement from the balance of the side weights,which were correctly set,so I was told.I own a Graham unipivot,and this is not evident in that design.I also felt the sonic performance was "TROUNCED" by the Air Tangent,even though he seems to be quite happy with the 12.6's performance,as it has a bit more bass(we are not talking alot more)and he is a bass fanatic!
Funny thing,is that he does not seem to be aware of the loss of instrumental body,and harmonic textures that the Air Tangent had.In SPADES!!Yet,I chalk this up to the "newness" syndrome.He is a very experienced/critical listener and I assume the sonic issue will sort itself out.
I'm willing to bet the performance will be greatly improved,if the "tick tocking" can be solved!
I find it hard to believe that the VPI (which dispels with any damping/bearing fluids)would be designed with this effect.Yet,according to my friend,it is NOT a simple adjustment to the side weights,and requires counterweight and possibly other set-up parameters as well.What gives?I still don't know if he has solved this.Or any of his "mucho experienced" audio gurus.
Any thoughts I could convey to him would be helpful.

Thanks!

So speedy, how does your dissertation relate to the original question or are you rambling again?

I'm a "rambling kind'a guy"!!So?A legit issue,on a related product.Some courteous 'goners may actually be of use,as to this issue.Then you can have your "black and white" issues sorted out!

the main difference is that the 12.6 does not have any damping or need for the fluid and the new drop counterweight. probably the new 12.5's even have that. other than that not much