I’ve had to deal with many old, shitty, trailers in my life. It is what it is. That said, they’re simple enough that “rebuilding” one is a lot easier than real mechanical work. Here’s what I’ve done so far.
Ball Hitch
The boat trailer has a 1 7/8″ hitch. I think such things are an abomination. I planned on swapping the hitch mechanism on the trailer to 2″.
Everything ought to have a 2″ ball except for the big stuff that’s 2 5/16″. Here’s the deal, if it’s huge and needs a 2 5/16″ ball you damn well know it. If it’s small and wants a 1 7/8″ you don’t have that on your vehicle because nobody does.
However, the part on the trailer was in reasonably good shape. Removing and replacing that part would probably cost $30 and kill a few hours. Besides, I have a cheat code. So I left the trailer as it was.
I highly recommend my cheat code. It’s called “Convert a ball“. With it you can switch between any of the three sizes instantly and without tools. It’s worth every penny. I have the slightly more expensive version that has a little box to hold your balls [insert joke here]. The box is a big deal. If they’re not in a carrying box you’ll lose your unused balls [ugh.. the jokes are too obvious]. I’m going to stop right now; just know the expensive 3 size system with the carrying box is money well spent.

Why do I have a second (spare?) 1 7/8″ ball? I have no idea. Why is the 2″ ball so grody? Because I use it 1000% more than the others.
Everyone should be awesome and roll around in a truck that be setup to tow anything of any size. Unless you’ve got a smaller SUV, then don’t mess around with 2 5/16″ anything. Seriously, you may think your SUV is bad ass but don’t argue with physics.
I assumed the 2″ ball was seized up and sprayed liquid wrench on everything. I probably didn’t need it. With a few taps of the hammer, the locking shaft mechanism worked pretty well. Wow! I wire brushed all the crud off just because I ought to.

Then it was effortless to install the 1 7/8″ ball. I added a generous glob of grease to stave off rust.
Not a big victory but a necessary step in the process.

Trailer Jack
The one on the trailer is absolutely shot. It’s gotta’ go.
I rooted around in my shop and found a new in the box trailer jack. I think I bought it 10 years ago to be installed in this very spot. That I kept it for 10 years and found it when I wanted it is a miracle.

No photos because it ain’t done yet. I’m pretty sure I won’t screw it up.
Tires
The tires held air, which is impressive after all these years. But they’re tiny 4.80-8 pipsqueaks. I could just buy the tires myself and mount on the rough but airtight wheels. But the bearings need repack. I can do repacking but I hate doing it, I always get grease everywhere and I’m never sure I did it correctly. Sometimes it’s best to just pay a dude.

I went to a super-redneck tire place. They’ve always been great and I’m glad I know them. One guy was more than willing to put tubes inside of my crappy old tires and send me on my way. I love that! They know it’s a boat trailer and some boats never go more than 5 miles from home to dock.
Not for me though. I wanted good safe new rubber. There’s weather checking on the tires that doesn’t show up in the photo. I know they’re at least 10 years old and they were probably old before I got them. Plus little 8″ tires spin fast, too fast for my tastes. So to spare me drama and worry, I asked for new tires and no tube.
So that’s what’s happening. If I were a true mechanical stud I’d mount the tires myself, repack right there in my driveway, and just testosterone the whole situation into submission. I didn’t. I’m waiting for the tires to get done. Two cheap ass tires won’t break the bank and $25 for packing is a fair deal.
I don’t have a spare. I tried to explain that to the tire guy and regret it. I over-nerded the poor innocent dude and now he’s got details floating through his brain. I’m not sure what he’ll do. I should have kept my mouth shut. I never quite learn.
I’ll update when the trailer’s back.