Ducati MONSTER S4R Owner's Manual page 54

Replace the bulb (4, fig. 56).
Note
Never touch the transparent body of the new bulb
with your fingers or it will blacken resulting in reduced
bulb brilliancy.
Insert the locating pegs of the bulb base into their seats
to obtain correct alignment; hook the clip (3, fig. 55) to
the headlamp holders.
Reconnect the cables.
E
To change the parking light bulb, withdraw the relevant
connector. The bulb (5, fig. 57) is of the bayonet-type:
press and rotate anti-clockwise to remove. Fit the spare
bulb by pressing and turning clockwise until it clicks in
place. Fit the bulb holder again and assemble the rim-
reflector assembly.
54
4
5
fig. 56
fig. 57