Normally I play bass clarinet but I've been playing alto clarinet in a clarinet choir for about a year and have tried 3 different brands: a Vito Resotone (plastic), a Buescher (plastic), and now a LeBlanc (wood) that's just been rebuilt. I just got a mouth piece from Roger Garret. As far as ease of playing it seemed the Buescher was best. The problem on the Vito and to some extent on the LeBlanc is when I play a low B or C in the clarino register (vent key open), if I'm not careful it wants to jump a 6th higher than the B or C I'm trying to hit . (The Buescher was better.) So if I have say a grace note on the high F in the chalumeau register (vent key closed) and jump to a C in the clarino register, it wants to go from an F to an A instead. Jumping to higher notes isn't a problem. It can still be an issue even if I start on the B or C instead of jumping to it but it's not as bad. There don't seem to be any leaks and different reeds may help but don't solve the problem. Is this normal? Is there an embrochure trick? I noticed that the bore on the Buescher was slightly larger than the Vito.