Hello Derek,
There is a facility on the KN7 for altering the Sustain settings and to do this you need to:-
Press: PROGRAMME MENUS
Press: PART SETTINGS
The screen will change to show the Sustain Controls in the centre. Before I had my Foot Controller, I used to alter it here and then save the setting either on it's own or with other changes I'd made, to a Panel Memory, then obviously when that PM was hit, the change would take effect.
Hope this helps.
Audrey