[KeefyB]

Originally Posted by mitchc

There is a spacer that fit inside the r/h seal between the bearing and the axle....it usually doesn't fall out that easily so it might still be there.

have a look at the parts catalouge here: http://www.ducati.com/bikes/service/parts/2004.jhtml?family=service&node=parts&modelName=200 4

If the wheel is re-fitted without the spacer the discs will probably foul the calipers. Worth rechecking it's there!

Good luck

Yep,I knew that,its just as you said,it does'nt usually fall out easily.
Only time mine came out is when I overtightened the spindle clamps and ovalled the spindle.