Spencer,
Might not be very relevant to your situation, but in some positions it is best not to lubricate. We have a Ford 550 backhoe loader at home. Father regularly greases all zerks except for the connecting pins on the front loader bucket. Runs them totally dry. I asked once why this was the case.
As a builder, loader very often is lifting and moving sand or grit. Sand gets into pins and bushes and wears them in no time. His operator had been driving these machines for 30yrs and could testify to the wear that could be caused.
Now you may never have the commercial work that these were put to, but the logic is similair.
We also had at one time an old Ford 4000 tractor. The balls would constantly fall out when no attachment on due to wear. We eventually had to weld on a shoulder to edge of the lift arms to prevent it occurring.