The meter appears to have two separate coils. If one of these coils is open, the meter might display the behaviour described.

But it looks like you'll have to start checking individual components. The CDS cells should read very high in resistance when dark, the reading should fall when they are exposed to a bright light. Check the aperture and shutter resistors too. It's a dirt simple circuit, a few minutes with an ohmmeter will tell you what's wrong.