I don't know anything about the new ones but I've been adjusting the old ones by doing the same basic maneuver, for quite some time. I clamp the lug on the back, that connects the stem to the back of the face, and turn the face to where I want it.
Generally there's not a problem with getting a close reading unless the thermos been damaged. Even then it can be recalibrated sometimes and read well enough cook with.
No thermos are needed at all after the cook developes a feel for the size of fire he needs and the heat its making(AKA Fire management). The meat can tell you how well done it is by the look , smell & feel alone and probing for tender can indicate doneness too.
The biggest problem with the thermos I have seen over the years is the users have themselves convinced they need the grill to operate like a submarine, with absolute perfection and sealed up tighter than a frog's ass.