bkay

Is this the screw you mean?

[ATTACH=CONFIG]618370[/ATTACH]

If so, I would use some kind of penetrating oil, like PB blaster. I'd lean the head back, so the screw was facing up. I'd apply the oil and wait overnight and try it again. If it doesn't work, then I'd lean the head back, put a screwdriver that fits the slot and tap it with a rubber hammer. I'd keep on doing the two aforementioned things until it came loose.

I'm not the most experienced person around, so wait for Janie or someone like that to agree with me or maybe suggest a better idea.

bkay

edit: This is not a 600e, it's a 600, so it might not be exactly like yours.