LowRyter recently posted a fun thread about the V11 appearing in Cycle World magazine. I just had the opportunity to read Cycle World's "Best Used Bikes", December 2017, featuring the V11 and an image of the Tenni. Working through the rest of the issue, I found something else relevant to the Guzzi: Kevin Cameron's regular contribution, "Ignition" titled The Long and Short of Fasteners. In his eloquent way of helping mere mortals appreciate applied engineering practice and outcomes common to motorcycles, he describes the reasons why short bolts or thin [sprocket] nuts come loose, especially when subjected to power pulses.
I was reminded of my recent input hub failure when the tabbed retention washer failed and the hub "walked off" enough to begin disengaging the clutch.
http://www.v11lemans.com/forums/index.php?showtopic=20037&p=223175
This is exactly the situation Kevin Cameron is discussing in his article (absolutely worth the read!).
So, it occurs to me that anytime the V11 gearbox input hub is exposed, it should be inspected, and (if necessary) retorqued, with a new "safety washer" correctly staked. { The special nut does, unfortunately, require a special engagement tool.}
No matter why your gearbox might be separated from the motor, absolutely see to this very simple potential failure point!