You do not need to remove those screws. They hold rotation limiters for the focusing helicoid. You can do everything from the point in disassembly you have already reached.
In the instructions I linked to, I referred to the rollers and to the cam plate where it contacts the rollers as what needed to be cleaned and regreased.
See that short slot on the left of the picture, midway up? One of the rollers is clearly visible inside it. It is through that slot and its counterpart visible in the picture on the other side that you will reach the old lube to remove and replace it. When you look into the slots while rotating the cam plate you will be able to see the edges of the cam plate, which contact the rollers and move them outward, and it is those edges you need to clean and relube also.
Along the edges of the cover plate are two semicircular slots: the one nearest the camera is bordered by the row of soldered wires. Through either of those slots you can rotate the cam plate through its full motion.