Difficulties while switching down

hello together… about 4 weeks ago I got a brand-new z800. the moped drives really well. there’s nothing to complain about. However, I have “sometimes” the problem that I can’t switch down anymore. And that’s…^^ if I roll to the traffic lights in the 6th gear and then be, say, 40 or 35 km/h, try to switch to the 5th gear and so on, nothing does. I step into the empty in the best sense of the word when I’ve come to the stand the bulge can’t be switched. For the first time 2 minutes busy switching into another way while the cars are already hopping on me. however, that only sometimes does it. Furthermore, I still think that if I in the first course roll, something grinds (scratching – grinding noise). but there also not always. the statement from the dealer was that she has to be driven in. that certainly can not be. last year have bought a brand new er6n for my wife and the purring. will be again on Monday at the H ändler pass by and complain to me. so if someone knows something or the problem knows, give off a suitable commi. because a dealer can tell a lot if the day is long… mfg wolfi