I had a used super swivel last me 3.5 to 4 years then it was leaking and I just replaced it. I might have been able to rebuild it but after greasing it, it just leaked more so that is the reason I just replaced it.
Most of the regular or cheap brass swivels will not last me a year so I don't use swivels on any reels anymore but the supply hose reel. I have a jumper from the machines to where the hose reels are and connect when the hose is let out. Once done working I depressure the hose then disconnect the jumper then roll up the hose.
This works great when doing large jobs and have to move the trailer around, I just turn off the machine, depressure the hose, disconnect and reconnect the hose after I move the trailer so I don't have to roll up the hose then unroll after the trailer is moved, this does save a lot of time.