As you say, this is not a new keyboard.
Maybe it's DD 720 disks used, and have to be formatted and copied into on Win98/2000
or early XP to work? Not a unknown problem on older Technics KN's.
If the format diskette funktion works on WK, try that before copy files into it.

GJ
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Cheers 🥂
GJ
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"Success is not counted by how high you have climbed
but by how many you brought with you." (Wil Rose)