Thank you GearBest for the comprehensive reply.
I do request a little better explanation as I think interpretation may not be quite accurate.
If I interpret this correctly, I think cutting of a trace is required.
Can we request Mr. Xu show a close-up photo of the modification?
Thank you again.
What do you mean by "solder should be open"? It is going to affect NiMH charging? I did get 1.48V if I remembered correctly. It is the Li-ION Charging that is having problem.
I just sent this message via PM to another member and then saw your post, so hopefully this may help you as well;
To quiet the fan that is in there now, pull off the black sticker (and throw it away) at center of fan and apply some light Oil to the center shaft. Just a little.
Sewing machine oil or electric shaver oil, etc. I use Mobil One synthetic 0-30w oil but any of the oils are better than none.
When that fan finally dies (or you kill via smashing it) this one will fit (with a little grinding inside charger mount) and moves more air, but they are all fairly loud, can’t help with that.
http://www.tmart.com/2510-Computer-Chassis-Fan-Black_p186231.html
Only $1.95 shipped!
The connector on the new fan is the same as original. I installed mine about 3 weeks ago and it fires right up and runs like a champ.
It is exact same fan size, just thicker front to back.
Other thing I did was prop mine up in the back slightly, it allows more air under charger and makes it easier to use since it is tilted towards you.
Hope this helps,
Keith
Why would you throw the sticker away? If you take it off carefully and not let any oil get on the sticky, put it back on to keep the added oil where it belongs.
gearbest - in the post above with the picture, the RED arrow doesn't point to a solder connection, or jumper. Can you confirm this? I think it should point to "J1", just above the center of the black blob thing. Please confirm if you can with Henry -- Thanx!!! This will be terrific if it works!
Those traces the pic points to go to the voltage selector switch.
And J1 is open in the pic and closed on mine.
EDIT:
I just checked my older v2.0 and J1 is OPEN
v2.0 on left and v2.1 on the right I think v2.1 was “detuned”
Well, in my case, the sticker was already deformed from excessive heat due to poor fan and the remaining oil had already got on to the sticky.
Also a lot easier access with it not there.
The new fan does not need maintenance so no more fumbling with it.
Ok - just cleared the solder blob from J1 and it did fix the problem!! 
The readings from the unit are now about 0.05v lower, so much closer now. I see only an approximate 0.02v high readings which is fine, acceptable to me, and makes it within the Opus spec as defined in the manual.
So, for those having the same problem, where the Opus 2.1 reads too high resulting in undercharging the cells by 0.05v or so (mine was about 0.06 to 0.07v), check J1 - if it's soldered close, opening it up will fix the offset problem by about 0.05v. I used solder wick to clear the solder off the J1 pads.
Thanks GearBest, thanks Henry!
This is good news. I ordered a 2.1 a while ago and was already preparing myself for disappointment. Now if the dang thing would actually move...tracking was generated 10 days ago but hasn't shown any events yet.
Thanks Tom! Now about that fan issue … 
Sorry, don't really have fan problems with mine, or the noise they make is not a problem for me. My chargers are in a well sound insulated room (basement office).
Question for those that encountered the issue with out of specs voltage reading: which plug do you have on your charger?
I would like to establish if this issue is present on all circuit boards or there is a difference between US and EU version.
Also, I presume that NiMH cells are much less affected because of the lower “fully charged” voltage!
I ordered 2.1V on October 8, my most expensive charger, was excited to get it, at least until today when I read about the issues:/
Hi,
could you please post a picture showing the results of the operation, I want to make sure of what I am to do
Good Day mmaghakian,
See dchomak's pics in post #325
Best Regards,
George
I don’t see any pics in post 325
what do I need to do to see them ?
Hi mmaghakian,
Unfortunately You will have to fix the problem in your browser blocking access to the pics...
But all is Not lost, the Pics are:
Best Regards,
George
Yes - those pics show it well. Thanks dchomak and George!
I am so embarrassed !
it was my browser
I compensated and now I see them in the post !
thanks for the lead.
here they are on a different pic.host:
Thanks a Bunch Keith! That is right on the money, replete with correct connector!
Well you may wanna load her up set to highest charging rate an stick around for a listen, because the bearing is so shot in this thing it causes the fan to come to a complete stop. Its passed a noise issue, it’s an inoperative fan issue. I’m actually glad I was in the same room with this thing charging a few batteries recently (I too have mine in another room for noise suppression) because this fan is definitely not going to last, and I don’t need house fiyahs.