I've taken apart ofther PS/2's and they had screws down the side of the top cover to loosen and then top cover slides off.

I've just acquired a Model 35 SX but it's not at all obvious how to take the cover off - it appears that it must slide, but it doesn't - is it just very stiff?

Thre is o thiumb screw at the back so that has already been removed.

I'm trying not to break anything because it's in great physical condition...

Anyone know how to do this?

TIA