Remove the shaving heads:

1. Switch off the shaver.
2. Press the release button (1) and remove the shaving unit (2) (Fig. 1). 
3. To remove the retaining frame, push the sides of the central spring toward each other (1). Then lift the retaining frame out of the shaving unit (2) (Fig. 2). 
4. Slide the shaving heads out of the retaining frame (Fig. 3).
5. Remove the guard from the cutter (Fig. 4)

Place the shaving heads back:

5. Place the cutters back into the guards.
6. Slide the shaving heads back into the retaining frame (Fig. 5)
7. Put the retaining frame back into the shaving unit. 'click'
8. Put the shaving unit back onto the shaver.