Remove the seat and turn it upside down.
Loosen the special screws (4), turn the plates (5) and open the seat cover (2) lateral sides to slide it out.

Removal of the seat
Reassembly of the seatDisassembly of rear shock absorber - rocker arm - linkage assembly
Undo the screw (15) and remove the rear shock absorber (11) from the rocker
arm (18).
Undo
Undo the screw (14) and the nut (21) and remove the linkages (10) and (12)
from the rocker arm (18).
The rocker arm movement is obtained by needle roller bearings (9) rotating on
a spacer (1 ...
Overhauling the rear wheel
Inspect the condition of the rear wheel.
As the wheel rim has no bearings, it should be supported using the service tool
code 88713.2951.
Note
This service tool can also be used to install the wheel on a balancing
machine.
Overhauling the wheel
Inspect the wheel as described below.
...
Front brake lever
Pull the lever (1, fig. 94) Towards the twistgrip to operate the
front brake. The system is hydraulically assisted and you only
need to pull the lever gently.
The control lever (1, fig. 94) Features a dial adjuster (2, fig. 94)
For lever distance from the twistgrip on handlebar
adjustment.
...