Here is an example.
This is the underside of the Minnesota A I have. If you'll notice just how built up and caked on the old oil is, well the 127 that started this thread was worse. At least with the Minnesota you could see the steel colored parts through the old oil, but with the 127 those parts were black with oil and you couldn't tell them from the black painted underside of the bed.
These machines were used and used and used and probably oiled with an organic oil such as whale oil or something like that that doesn't respond well to kerosene and never wiped down or cleaned. That's about the only theory I have right now.
Joe