It is part number 79920772A oil bypass spring.
Here is a picture of one that has no deformation,
Obviously a stolen pic from Ebay.
Dealer replacement price: $10.99
I was hoping to send you to Ebay to buy it from Gotham but their price is double that for a used item. I would normally have recommended them.
Use this parts fiche, http://issuu.com/ducatiomaha/docs/ms...ine&mode=embed
Page 26 for a line drawing of it and how it is mounted and page 27 for part numbers. Looks like a small piece of pipe unscrews and is a quick swap for a new one.
Good luck and I hope that helps you.
And no, I do not know why it is dipped in rubber, nor why it degraded. Generally a bypass spring is there in case the filter gets clogged, then the pressure won't build up and blow out the filter. It will keep circulating throughout the engine until the filter is changed out.
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