In a recent ride, about 9 days ago, I was pulling the trailer after taking it to carry some tools to help my wife's friend install a deck umbrella and on the way back home I heard a bad sound from the trailer. I knew it wasn't from the bike but was definitely farther behind me. After unhitching the trailer and as I pulled it through the garage that sound persisted. I had a bad bearing in the wheel. I ordered the axle kit from Uni-Go 2 days later since I figured it was all original equipment from 2002 when my trailer was made... AND when I removed the wheel the spacer inside was rather rusty. The kit arrived 4 days later (not bad for Jacksonville to Iowa). It was installed right away. I noted that while the bearings were very tight as they should be on the axle the wheel was able to move about 1 mm side to side. Not a wobble but side to side sliding. After verifying with Uni-Go tech support and a few others I took it apart again and added some RED Loctite around the bearing where it contacted the wheel hub. After another day to let that cure (yesterday) the wheel is very solid with only the slack in the bearings that can be felt but not seen (a good thing). Went for a ride with the trailer last night and all is now ready for my LD trip in a few weeks across 4+ states (Iowa, MO, IL, KY, TN). I say 4+ because I'll just be crossing the border from KY to only about 10 miles into TN.
The hitch is working great and the trailer tracks perfectly and smoothly behind the bike at any speed up to a tested 78-79 mph. I likely won't be riding that fast with the trailer... much. The trailer tire has a speed rating of L which is 75 mph (although I've read of several riders I know personally going past 100 with the trailer in tow and no problems... mechanically). I tend to stay off the Interstate highways whenever possible preferring the more interesting and lesser traffic of state and county roads.
Now, to work on preventing that tendency to over pack the trailer.