I was looking ways to fix many hardware problems for my old friend ketron I am using for the past 16 years (screen has so many black lines that is un-visible, buttons and keys don't respond as is should be and hard drive is giving me hard times with corrupted and unknown files.
so i have solder many times new buttons and replaced the rubber under keys i tried replacing the HD with a SSD (some ebay IDE style) or with Compact Flash memory. Seems that the controller is not able to handle fast drives or to read memory chips although seem that formats this types like normal HD.
Any way all made me find a second hand SD1 just to have a clone of my instrument and my work in case of Fatal hardware failure
The NEW (because the previews owner never touched this instrument) SD1 came with OS Ver 1.0 !!!! and only original styles and sounds. sounded louder more live bright and all buttons had an instant respond in light touch
I compared both instruments on a mixer same style same sound or even the demo songs they were unsimilar.
but the problem was that the new styles from plus i had modified and my midi sounded strange in a bad way.
SO i decided to upload ver 4.0c standard it was difficult to find a Flopy disk for that i used the cable to upload the files in ketron and then to floppy and do the firmware update.

Why I am sharing all this ...
the new keyboard transformed now in a well balanced machine but the buttons don't respond as they were its slow like I always remember my old ketron and you have to press the buttons slowly or in many cases 2-3 times to get to menus