Yamaha CS80

Greetings,
Thanks for your access approval to this group. I'm happy to help others in anyway I can!! I, too, am in need of some assistance for my beloved Yamaha CS80. Maybe you can help?
The Strings 1 & 2 Presets no longer illuminate. We are having a difficult time trying to sus out how to remove, disassemble, open the housing that holds all of the bulbs for all the presets. Has anyone replaced these and could you tell me how this sort of rectangular housing is opened / removed to gain access to the bulbs?
Thanks,
Jerry