I'm in the process of servicing the clutch on my NC35, replacing friction plates, steel plates and springs.

Today I was reassembling the stuff. When I tightened the clutch nut, I heard a large POW! sound after tightening the nut for a bit. Heart attack, afraid that I'd busted the splines. Removing the clutch nut, no visible damage.

I tightened the nut again, and thought I would pull the clutch lever to see if something had changed. Did so, and noted that absolutely nothing happened. I can turn part no 6 in this picture with my hand. Is that normal? I'm afraid to do anything more before I know what that sound was...

I would really appreciate any help, as the season is beginning here now...

I think that might depend on which way you tried to move it. Does the clutch lever feel normal, or does it just flop about with no effort? Have you checked that it operates correctly? If not, I'd take the clutch back off and see what's going on with the operating rod that is operated by the part you moved by hand. Or, take the cover off that the part comes out of. Perhaps the rod isn't sat in the right place and the noise you heard was it slipping past the notch it sits in?

There is a little grommet in the case where the actuating arm rotates and pushes onto the clutch rod - the little grommet thing, probably, has come out.

no8 in that diagram.

if the clutch pack is in and tight, the nut is torqued down then put it all together and see what goes on. You have to align the cut out in the actuator arm with the grommet and the rod. bolt it all up and then test it

Well, today I took it all apart and inspected. A friend said it could be one of the friction plates that broke if it wasn't mounted correctly.

Found no sign of damage. Put it all together and it seems to work fine. No idea what that sound was, I guess it was when all the friction plates and steel plates were forced together or something.

Case closed. I'll start whine here again soon if I missed something... Thanks for your effort.

Well, the problem has vanished. Ran the bike a good 100km the other day without any mishaps. Works like a charm. EBC clutch with Motul 5100 semi-synthetic oil made shifting gearss smooth like butter on my bike.