Fairlight-CMI

How do you open the case of the music keyboard? I want to get inside to clean the 
backs of the keys which are quite dirty and I can't reach it with the vacuum 
attachments I have unless it's open. I also thought it might be a good idea to see if 
any dust has accumulated inside and vacuum that out as well.

I removed teh 5 screws on the bottom of the front. I also removed the 5 screws from 
the back under the top lip. The case is loose now but will not come off. I don't want to 
mess with any of the screws on the bottom until I know wexactly what I'm removing. 

There appears to be 5 large screws with big washers under there in exactly the centre. 
Is this what I need to remove?

Thanks...

Jerry