PC3K8 Kurzweil issues

Hello people,
HNY!
I am desparately in need of a service manual for a PC3K8. All i can find is a PC3x. Are these the same??
I need an encoder potentiometer which is failing…anyone else have this issue?
Thanks

https://kurzweil.com/pc3k8/#support

The PC3K service manual is an addendum. The previous PC3 manual applies otherwise. You can get the encoder from InstrumentalParts.com. It’s a bit pricey but easy to do. As to why, impact and/or wear. Mechanical parts wear out.