Of note: I added some extra info about these relays to that link Noobed2336 just linked to above:

  • A Western Electric document, dated 1979, describing the internal details of the 327 type relay, and its many revisions, and mentions the potting compound that is the likely culprit
  • Some entertaining photos I took while de-soldering a 327A / 72K relay from one of my old 400D cards, and the gooey results of its innards!


I added some other details there.
The relay seems to hold a large amount of this goo, probably on the order of a shot glass or so.