It could also be a boot problem . All of those synthesizers have a boot rom chip . It stores the operating system on it , which tells the synthesizer what to do . Before you open it , try a hard reset first . It is usually a matter of holding down a series of buttons while turning it on . It will erase all the altered programs and reboot the factory settings . It will be in the manual , if you don't have one , check the synthzone's links for Yamaha and you will find one . If that does not work , sometimes removing the boot rom chip and then resetting it also clears out the problems ( SOMETIMES ) . Because you essentially kill the power to it for about 10 seconds or more . I had to do this to my Alesis Wedge , it worked perfectly after that . Usually this boot rom chip is labeled with the OS version on it . But , try the reset before removing anything .