Take care that you don’t accidentally desolder the internal wires.
Switch board 1:
Wires 1 – 16 get soldered to key contacts 1 – 16.
Switch board 2:
Wires 1 – 16 get soldered to key contacts 17 – 32.
Switch board 3:
Wire 1 gets cut.
Wire 2 gets soldered to the common connection (bus bar).
Wires 3 – 14 get soldered to key contacts 33 – 44.
Wires 15 – 18 are not used.
Wires 19 and 20 get cut.
