Ducati MONSTER 821 Workshop Manual page 1146

Reuse the generator cover or a service cover with puller (A) no. 88713.1749 duly fitted.
Secure cover to crankcase half with some of the original screws and begin separation by turning the central
pin of the tool.
Tap the end of the gearbox secondary shaft with a plastic mallet to separate the crankcase halves.
Note
Take care not to lose the shim washers on the shafts and on the selector drum.
Remove the gearbox shafts (5) and the gearbox selector drum (6) from the crankcase halves.
Slide out crankshaft (7) using a plastic mallet and taking special care to the single shim (8) positioned on
the clutch side only.
Remove the timing layshaft (9).
Collect the O-rings present on the crankcase half.
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