If it was me, I'd replace it. Reason I say this is that I had 1 go out my daily driver about a year ago. I had just got our property and was idling around checking out the scenery. Then all the sudden my passenger side front hits the ground, digs in like an anchor. It was the lower ball joint on my 96 Taco that gave way. Just 20 minutes earlier I was cruising down the highway @ 70 plus mph. I was lucky it failed when it did, no warning, no squeaks...notta. I replaced all 4 on my truck and would suggest the same to you. Ball joints are not the place to cut costs, typically if 1 is failing the others are not far behind.