SEF 300 noisy

Hello,

my SEF300 MY 2023 was very loud from the engine right from the start. The oil was always clean, I didn't worry about it. I bought the bike new.

It always sounds like a clutch rattle. Whenever I let off the gas I hear the rattle. Valve train can also be heard loudly.

My dealer said it could just be the cam chain tensioner.
He told me to pretension the cam chain tensioner a little more and then screw the spring back in.

Is the issue known?