Same thing happened to me when I changed my ball joints. Passenger side started leaking. I was convinced the seal was ok (low mileage) ... so I bought chromoly axle shafts & wheel bearings (since I was taking it apart again).. Like an idiot I left the plastic guides installed the first time and it was all chewed up.... I used my old jeep antennae with rags tied to the end... and cleaned all the dirt out of the tube... then with fresh rags gently cleaned the seal and then added some oil on the rag to coat the seal.... No leaks since.... One tip... do one side at a time and raise the side you are working on a little higher to keep the oil out of the tube.
Note: before I did all that... I disconnected and raised the opposite side... and let sit for a while.... then drove it for a week... to see if it was just oil in the tube.... it still leaked, so I knew the seal was pinched, had dirt on it... or bad.