Today I replaced the way wipers (made of thick wool felt), which led to a discovery. The carriage had always left a trail of black oil on the front V rail as the carriage moved back and forth, and I had thought it was the old wipers drooling. Not true.
What had happened is that there was a mass of impacted chips glued together by spooge and dirt in the space between the top of the V-shaped bed way and the deeper mating top groove in the carriage. Cleaned out with a long piece of flat spring steel.
Also had to replace one oiler, as the chips had packed the chamber and could not be disloged with the piece of spring steel.
Joe Gwinn