For my trailer jack (a larger 5K square weld-on drop leg), I used another jack to get the front end of the trailer up, then unbolted the handle, and then the inner part of the jack dropped out of the tube (the part the slides in the outer tube, along with the screw in the center). Then I spun out the screw a bit and greased it, along with greasing the thrust bearing mounted on the top of the screw. Reassembled and it works much smoother. I'm also looking for another bearing for the top, as I found it was completely dry and rusty when I took it apart, so it likely had little or no grease on it to begin with, while the screw itself still was pretty greasy/oily.
Put a jack stand under the trailer, and removed the jack from the trailer so I could get a better look at things.
As seen in one of the videos, my screw shaft was squared off a bit and wouldn't slide out of the outer tube, so I filed it a bit and it popped right out.
The screw unwound fairly easily, until it hung up at the end (won't come out of the inner tube). Looking up inside, it appears that the screw shaft has a head, and it isn't meant to come out that way, so I'm not forcing it. The jack will probably never be extended far enough to worry about it.
At the top of the screw shaft is a bushing (thick washer), and bearing (a really, really thick washer, not a ball bearing setup).
Picked up new (Grade 8) hardware on the way to my son's Little League game, working on it now while cheering along. Was able to find everything but the bearing, will clean and lube the old one.
Gave everything a quick wire brushing (by hand), will reassemble with anti-sieze and call it good. Don't have time to paint it, just want to see if I can get it functional again before worrying about cosmetics.
It's all back together, I'll get it back onto the trailer tomorrow.
More pics, but I stopped once the lube started and my hands got nasty. In the back of my head, I kept hearing: "Goober it up!"
Anyway, that bearing is a little puzzling. It has an inner recess on one of the flat sides. I didn't notice that when I took it apart, so I have no idea if the recess is meant to face up or down. I left it facing down when I reassembled.
I don't know what you mean by inner race in this case.
The bearing appears to be a solid piece of steel. It doesn't look like a ball bearing that fused itself together. It was tough to remove, bit wasn't rusted to the bushing.
In the two videos I posted above, my bearing looks more like the first, which the (DIY) guy refers to as a washer. The second (Dutton-Lainson) video shows a ball bearing. I looked at their website, and they do sell a thrust bearing as a replacement part, but I don't know if it will fit my jack.
Random update: Haven't used the trailer much since unloading that firewood in early summer. But, I've had to move it around the yard for leaf cleanup, and used it to pick up a new-to-me Trac Vac. Very happy to report that the jack is still smooth and quiet!
I missed your response earlier, about the bearing/washer. To me, from those pics, it looks like a seriously rusted up bearing, as it has machining features that make no sense and make the part more expensive if it's just a hunk of metal (the cut ridge around the outside on one side, and the one around the center on the other side).
It looks like a really rusted up, filled with crud, ball bearing, like the one that is seen for just a second or two, right at the 1:00 minute mark of the video in post #7.