I hope this is the right forum - not strictly camera repair, but camera-related repair!

I picked up a Minolta Spotmeter F for about US$10. It is in excellent cosmetic condition but does not read correctly - at ISO 100 it always reads 2.5 EV, at ISO 200 3.5 EV, and so on. Other than this minor flaw it seems to work perfectly, so the probem is probably in the sensor and related circuitry, not the microcontroller.

I'm fairly handy with a multimeter and soldering iron so plan to see whether I can repair it myself. However it's not obvious how to open it up. There's a serated strip over the middle of the top surface, which I suspect may cover up screws for access. Does anyone know if this is correct? I don't want to risk cosmetic damage pulling the strip off (I suspect it is glued on, though not entirely sure) if it's not the right way to open the meter.

Also, if anyone had a schematic diagram or service manual that would be really useful! I have the user manual.