Casio PX-160

All white keys have been confirmed to produce sound.
Of the black keys, the 6 keys from the left do not produce sound.
The 2nd black key produces a sound that seems to fade out.
The volume knob is unresponsive.
The volume is at its default setting.
This is all that has been confirmed.
All other keys have been confirmed to produce sound.
It has been used for practice, and I believe other functions are working.