Everyone says the axle and bearings look good but i might disagree. In the first and last picture of the axle it looks like there is some galling of the metal axle where the inner race rides. The bearing should be spinning the balls between the inner and outer races not spinning the inner race on the axle shaft enough to cause the galling of the metal. Slight wear marks on the axle where the bearings seat is normal but the galling indicates that the bearing is seizing up at times and being forced to spin on the axle shaft and that not right. Unless what I think I'm seeing is just dirt, grease and gunk, I'd replace those bearings now and try to sand the galled spots on the axle with a little emery paper.