Need to open up pfaff 7570 by the balance wheel

Question

I was trying to open up the machine to put WD40 on the balance wheel (as suggested because of bobbin winding problem) when I think I lost a tiny bolt down the machine I was unscrewing a tiny s***w when I heard something drop. I don't dare use the machine until I open that up and make sure nothings lose inside. Can you help me?[e-mail]