I just sold my Casio PX-A100 and the buyer found out that the on the last octave keys are out of tune, tried going to default settings. Out of tune keys - A,B,C - the last keys of the keyboard + weird thing with F key.
When shifting octaves those same keys continue being out of tune (same sound).
When F key is held, the B key is not working. This behavior occurs for several combinations: (C(#88) <> G#, G <> F).
All of these issues are localized in the last octave )
It almost feels like there is a shorted circuit between these keys.
Have anyone encountered this kind of malfunctions? How did you fix it?