About six months ago, I bought a wooden moving fillister plane on ebay. It's a design I hadn't seen before, but looked like it was in pretty good shape, and the seller was able to confirm that all the parts moved the way they should.
Also something I hadn't seen... those lines on the side of the body are depth markings. They're perfectly parallel to the sole, and are mostly in 1/8" increments. It's not perfectly accurate, but it's close enough for a rough setting.
Once I got it, I touched up the iron (it still needs a more thorough sharpening, but it's workable), and gave it a try. On long-grain cuts, it worked quite well. It showed a little bit of tendency to jam, but was otherwise fine. On cross-grain cuts, it was pretty bad. It worked, but the edges were ragged. After a little poking, I realized there was no problem at all with the nicker: the slot is worn enough that it needs a shaving for padding behind it, but other than that it's fine.
The problem was that the iron wasn't original, and was too wide. On a moving fillister plane, the iron needs to line up pretty exactly with the nicker. On this plane, the iron extended almost a full 1/16" beyond the nicker, which mean the nicker couldn't do its job.
So last night I spent close to an hour filing down the outer edge of the iron. I could have used a grinder, but I hate using them and I didn't want to risk overheating the blade. Eventually, I got it down to just about the right width, and it works far, far better now.
It can always get better, but right now it's in perfectly useable condition, at least in soft woods.