5 yrs ago when I was flushing the Oil out of the cooling system from the Oil Cooler fiasco, I noticed my Block heater was wet and green around it. Removed it, and it was the Rubber "O" Ring that was at the end of it`s life.
I did replace it with a new one, but probably the "O" Ring could just be replaced if it could be sized matched with a new one.
The BH it`s self, probably still good. They aren`t something that gets a lot of use. They are like a heating element in a Hot Water heater, as long as they are in the coolant or water don`t burn out.
If you need just the power cord, the part # Zero Start 3600010.
Saw it on Amazon, $43 and E-Bay $24.
Just do your searching. Always good to have a spare incase something happens.
Just went through this on my 82 Mercedes, cord and the Alternator met, and took the end right off.
Checked my 7 spare engines and not one had a
Block Heater.
Out of my 9 cars in the yard only one had a BH and a Cord, but the da mn Mice chewed up the wire. OK, just cut, strip and solder it together.
Center wire is a green with good shiny copper wire. (Ground?)
other 2 are molded in with the black rubber cord with no insulating cover. Just this, black thin looking wire, maybe steel?
Can`t solder it, tried on a small Walmart Vacuum cleaner with same kind of wire.
Twisted the wires together with wire nuts, and it still didn`t work, worked before.
Ordered a whole new BH just to get the cord, couldn`t find just the cord.
Iam pretty sure the one for our IDI`s is exactly the same, as they all are probably Zero Start, Phillips/Temro BH`s.
Goat