Go buy some swivel grease STC3435, one for each side.
Remove the fill plug, at the top of the swivel (thats the shiny bit on the inside of the wheel hub).
Now remove the max level plug. Open one swivel grease sachet and empty it in until grease starts to come out the fill plug. When that happens, stop and put the both plugs back in.
Repeat for other side.
Now take a look at both sides. Is there evidence of leakage from the swivels? If yes, then its time to take it in and have the seal replaced.