On every yamaha arranger KB I ever had and I have had many of them....the first thing I do out of the box is to get a
"WHITE OUT PEN" and fill in the "little notch" on the
Master Volume Knob,...I also do this on the back of S950 on the gain Trim Pod next to the Mic input. This little tip will make your playing life easier for sure either at Home or on a dimly lit gig stage etc....

Simple cheap & very effective

Enjoy

Dp