Modern Vespa

The sound in the videos certainly sounds like something's caught under the flywheel cover, or as you hinted, the flywheel cover has been bent too close to the flywheel and is rubbing against it. I'd remove the cover and check where there's signs of rubbage, then bang it back into place.

I've had several 7-spring clutches spread on me before, but I thought Cosa clutches were basically strong enough to withstand tuned engines. I have those on my 172 T5 and my 225 P2, and was pretty confident, until I saw your pics

BTW, 42 Nm torque is for castle nuts; on a Cosa clutch with a decent HH type nut, you can do 60 Nm - I add the wavy washer and some medium (blue) loctite to make sure it stays put.

I made a little tool to pull clutches off easily with a screw and a little piece of alloy, which I insert under the clutch and screw against the crank to lift off the clutch, which saves me a lot of time whenever I have to work on a clutch or disassemble an engine. I'll post a pic if anyone's interested.

<== that would be me! Tnx.

...and i'd like Voodoo to see the picture of it as well.

I am interested in that clutch tool, too, because I am almost sure I will need it as soon as I will want to inspect clutch again. Sadly during the last weeks I had no chance to dig deeper in to my cosa so it's in the garage (starts OK, but clutch is dragging and the sound is not good IMHO)
I will update this thread as soon as I will progress - An I am sure I will need some advices too

I made a little tutorial for those interested in more details

Here's the "tool":

It looks grossly made because it was done in an emergency, and it's so well served its purpose ever since that I've never felt the need to make a more presentable version but rest assured it pulls even the most stubborn clutches in seconds, every time.

VERY grossly made, but... Solid welds!

Tnx again. Gonna weld me a nut to a stout piece of flat bar w/ a hole in it.
Should work.