Is there not a small screw on the front bottom where the needle pivots from or is it behind the meter face?
Oh crap......I just Googled that meter. I see your problem. The adjustment points are behind the meter case. not a good design at all. You will need to pop the case apart to do that so unless it is WAY off I would leave it since the accuracy will not be off by more than a hair anyway. that is unless you are comfortable with tearing it apart.
...oh crap......I just Googled that meter. I see your problem....