Vivitar 43 Meter Calibration?

I was recently given a Vivitar 43 meter. It's great because it has both reflective and incident, is light, and seems a bit more rugged than my Sekonic L308 (not to mention cost a lot less ).

However, near as I can tell it's about a stop off. On my old analog Sekonic there's a little screw to adjust the meter. Is there anything like that hidden somewhere on a Viv 43 meter?

Thanks!