Opening a Marantz CD-48

I've got an elderly Marantz CD-48 CD player that is regularly struggling read a disc or will on occasion reject the disc partway through. I want to start with a good clean-up and hoping someone here can tell me what kind of screw driver I need to get these unusual (to me) screws out.
I suspect a recent development of distortion is also partially down to the player, though I'm pretty certain the caps on my amp need replacing.
Cheers all.
 
Right... got hold of the correct tool to get the seven screws out. Looking at the schematic for the identical Philips model the cover should lift back, up and away. It wont release from the front panel though and peering through the gap from the back with the top lifted it seems interlocked. Should it come off with a bit of pressure or am I missing something? Don't want to risk forcing it.