Do you keep your KN7 closed with a dust cover on it? I do, and it is always plugged in to power but turned off at the keyboard switch.
Today I found the keyboard was on when I uncovered it and the top was pretty warm in an area that is probably below the transformer.
I wondered how it was turned on, but in looking at the switch I see it projects above the plane of the surface.
I had set a music book on it earlier in the day and apparantly this had depressed the switch.
I don't know about this keyboard suffering damage from being on while covered but I can tell you about a printer that fried itself being on under its cover.
Something to be aware of
Best to all
Bebop