Fox,
I had a similar problem with a Kn2000. I found that a sudden surge in the mains voltage had taken out a power supply.When I replaced the blown semiconductors in the power supply, it still didn't work.
The Kn2000 had multiple power supplies, which seemed to all be functioning.
What I found was that each power supply had a 1/8 watt fuse resistor that had blown from the ripple effect of overload. When I replaced all of the fuse resistors, all was well.
They are hard to find because when they blow, they do not burn or change color like a normal resistor that has been burnt.
Good Luck,
Walt