This is a very interesting topic. Going to class a few weeks ago I had to do an emergency stop. When I took my machine (bernina qe) out of its bag the handle on one side had gone under the top piece. The class teacher came and started to undo the side and take it off as well as the back . I was informed how dirty the top inside was and I had not been cleaning it. Like all of you I only did bobbin etc areas. Do we have to undo all this as well and clean? Ps machine repaired ie handle pulled correct by the lawn mower man across the road. The best£2.50 I have spent for a long time.