My clutch push-rod is exactly the length Luddite said: 335mm.
The top-hat pusher in the clutch cover bearing is clear and the rod slips past the (Viton) O-ring and seats nicely.
Speaking to Oberon on the 'phone, they confirm that the spacer is not inserted by them. Naturally, the lady I spoke to said they've never encountered such a problem! Steve Street, the Oberon director, said it was a new one to him but subsequently found a thread on Ducati.ms that showed others had had problems too.
https://www.ducati.ms/threads/pushro...ng-for.296561/
I shall look through that and see what conclusions I can draw. Steve recommended buying a new 'correct' pinned push-rod to gain the maximum rod protrusion of 35mm, rather than 39mm that the 335mm rod provides.
We''ll see...
Nick