Prepare 6 bolts assembly by inserting lock washer (#C), then flat washer (#E) onto bolts (#A). Align seat panel (#4) to the holes of the left and right arms (#1,2). Secure with bolts (#A), but do not fully tighten. Prepare 4 bolts assembly by inserting lock washer (#C), then flat washer (#D) onto bolts (#B). Align back panel (#3) to the holes of the left and right arms (#1,2). Secure with bolts (#B) and fully tighten all bolts (#A,B).