Perhaps the data in the flash of memory simply deteriorated? The old Casio support site is still working, you can download the "All data" file and restore the factory settings of the synthesizer. https://music.casio.com/e/data_ex3/
Hi all .
Where can I download the advanced data on MIDI Implementation for Casio CT S1 ?
The synthesizer operating guide indicates a link https://support.casio.com/global/en/emi/manual/CT-S1/, but there is nothing there.