I have an expensive medical device that works perfectly and is in
pristine condition, except the insulation on the power cord has
cracked slightly just where it enters the machine (it was bent over
too sharply once when packed for travel). The thick outer insulation
is cracked about halfway around the cord to the extent that you can
just barely see the covered wires inside the cable. The cable is
permanently fixed to the machine (doesn't unplug at the machine end).
It is round, and about the diameter and quality of a computer power
cable.

I need a way to seal up this crack in a neat, workmanlike way so that
it will not continue to fray, and so it doesn't look like an
electrical hazard. But what to use? I now have a turn of plastic
electrical tape over the break, but that won't do for the long term.

I simply don't dare open the device and shorten the wire. If I were to
break the machine it's like tossing $800 down the toilet.

A little plastic tube about 1/2" long over the crack would be best,
but I can't slide a typical heat-shrink tube over the area without
cracking open the machine and removing the cable to slip on the tube
-- which I don't dare do.

There's no electrical danger from the crack, as the wires inside are
still insulated from each other and it's a tiny crack. But if we have
to take it to the hospital, as occasionally happens, I'm concerned
that someone will balk at letting us plug it in because of the cracked
wire. Hospitals are so rule-bound about patient medical devices that
this is a real issue.

I've thought about liquid electrical tape, but not sure that it will
be neat and tidy. And will it be thick enough to fill the crack? And
will it hold? I want a finished look as well as a bond strong enough
so it doesn't crack again easily.

Any ideas? TIA