[Alan Brinton]

I’m a bit confused jumping between threads, but I see that Daren has brought up the phenomenon I was just talking about in the other thread, and he deals with it as I do.

I doubt that your Yamaha is defective. They have excellent quality control. One thing you could check, though, is whether the spacing is even between the keys, which is easy to see and to adjust. If you take it apart, you can also inspect to see whether any key mechanisms are misaligned, though that’s unlikely.