Help, please! Nighthawk Hotkey PCK4V KVM

I was given an old Nighthawk Electronics Ltd. PCK4V KVM recently, and would
very much like to use it. BUT there was no manual, there is no manual on
the net, and the company seems to have gone bust last year so there's no
chance of getting information from them. I opened the box up, and
discovered that it had actually been designed and built by "Digital
Developments Ltd.", from Dorchester. There was even a phone number inside,
which I tried, only to confuse a pensioner. Clearly, that company is long
gone too. I've tried the similarly named Locke's Digital Developments Ltd.,
from the other side of Dorset, on the off chance, but have had no luck.

I've tried various key combinations, to no avail, including
CTRL-CTRL-number, the same with scroll lock, etc..

The unit has a key on the front which can be turned to SET-UP, NORMAL and
LOCKED mode. I've tried various things in various combinations, and found
that if the key is turned to set-up, SPACE and RETURN change the visual
settings on the LCD and the squeaks change. But I haven't a clue what any
of them mean, and can't seem to get any setting to actually do anything;
none seem to have an impact when I attempt to switch between machines (in
NORMAL mode).

So I'm hoping someone here can help me.

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