I have a Bosch SGS43A18GB/27 probably similar. the top cover slides to the rear about 50cm an then lifts off. It is held in place by two clips, these are molded into the top cover (white plastic) frame and will be found at the rear. They clip into a fixed translucent fixed plastic bracket on either side. They can be released one at a time by; apply firm pressure on the top cover towards the rear of the machine take a flat bladed screwdriver (4 or 5mm blade) and push between the clip and fixed plastic. Now twist until top moves and the clip is released, repeat for the other side and the cover is off. The side cover on our machine is released by removal of two torx T20 screws at the front edge, it then swings away from the top and lifts out from the bottom. I hope this helps, don't know about you but I hate wearing marigolds...
Tony Ferguson, April 2007