I just acquired an OM2 which I don't know much about.
What are you using for a battery, or is everyone just skipping the built in meter and using something else?
You need a battery for an OM2 - otherwise you are restricted to one shutter speed.
Here is a website address that has loads of info, as well as a downloadable copy of the manual:
The EPX76 referred to as a battery type is the same as an SR44. Try to avoid the alkaline versions (LR44). Other posters here have recommended this site for the SR44 batteries:
Have fun - they are wonderful cameras.
You should use (2) MS76, KS76, SR44W, G-13, 303, 357. These are silver oxide cells. Do not use alkaline (A76, LR44) or lithium double cell (CR1/3N) as they came out after the camera was designed and 1) cause a 2-3 stop error in the meter needle position and 2) can cause the dread "clack" of shutter lock.