Read the manual linked above. If it has a light meter, it's likely battery-powered. That battery's even more likely to be dead. If the meter is dead, either a handheld meter or phone app meter is necessary.
Buy the cheapest 120 b&w available(Ilford XP-2 Super is good). Trust there's a nearby lab?
I'd buy two rolls. One will be sacrificial to learn loading/advancing/unloading. Get that down before actually shooting.
Finding a CLA tech is easier said than done for offbeat oldies like this. They're totally mechanical. Commonly, shutter timing can be off due to gunked-up lube in the shutter train. Try it at the slowest speed and work your way up. Little or no difference in speed is audible, e.g., if 125sec sounds/looks like 1/8sec, you've got a problem.
Good luck. Tell us what you find?