Proceed as follows:
1. Unscrew the screws Pos.2 and Remove the head cover Pos.1 (look at the Pict. 5.5)
2. Loosen the four nuts Pos.4(look at the Pict. 5.5)
3. Loosen the nuts Pos.5 (look at the Pict. 5.5) to loosen the belts tension
4. Unscrew the screws Pos.56 (look at Pict. 5.6) and remove the piece (Pos. 13 in the drawing enclosed)
5. Remove the pulley Pos. 62 (look at Pict. 5.6)
6. Unscrew the screws Pos.1 and remove the spiral Pos.2 (look at Pict. 5.7)