That photo brought back memories.
Where I worked we had a number of Kearney & Trecker S15 milling machines that had an oil sight glass on the front of the saddle. I was in the maintenance foreman's office one day when a charge hand from the milling section came in and told him that oil was "pi$$ing out the handwheels" of one of his machines. Turns out that "Bionic Bob" from the maintenance crew (who had been given the job of oiling the machines on the basis that it was too simple a job even for him to screw up) hadn't realised that the sight glass was bunged up on that machine so poured in "a bit extra" on the oil change because he couldn't see anything in the sight glass