Roger, I think you're confusing one bombing plot episode with another. The bomber was upstairs in 'State of the County' in season 3. These pictures are out of chronological order, but hopefully make more sense this way. We never see the bomber leaving the ground floor, but we do see Daisy starting to ascend the ladder. It's difficult to tell from this picture, but if you watch the scene you can see it's the ladder near the top left of the General in the plan view that Mark originally posted. This is the top of that ladder (we also see Daisy reach the top of the same ladder just after the previous picture). It looks like the back wall is closer to the ladder than it was downstairs, so maybe it's a partition. The walls are decorated with various car parts, and there appears to be some kind of bed in the bottom left. As the bomber walks to the front he passes the side wall which has several cardboard boxes and suitcases along it. The position of the wall would indicate that it's the left side wall of the gararge. At the front there is a window and an old gas price sign. This should be the window that is above the office. In the bottom left is the other end of the raised wooden divider that can be seen in the picture above. The final picture shows the bomber looking out of the window. It should be the left window, but is clearly the middle window because it's above the 'Service' sign. I'm not sure if this is just a simple continuity error, or if it's because they couldn't get the right shot of the window above the office.