Unless the photo cell has been physically damaged that part should be OK. However there are many other things which have more than likely gone wrong with it. To test it, take it out into good sunlight. If memory serves me (It's been avery long time!), the meter is activated by a button on the side. Hold the button down for several seconds in good sunlight and you shoulkd see the needle slowly move across the dial. Where is stops is your f stop. Since it is activiated by sunlight, you may or may not get a reading in dim light. Activate for a good 30 seconds, or until the needle stops moving. If it works at all, test it with a more modern meter to see how accurate it is.
Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats.