All of the windows are the same. The windows and frames are metal–no wood. This is a house. I have added two more photos to the gallery at the previous link. The first shows the hardware at the top of the sliding window. This is a little plastic gizmo that travels up and down with the window and does not move otherwise in any way that I am able to see. The second is the top of the track that the window slides up to, where there is a metal thingie. Said thingie appears on both sides of the window.
I’m still trying to figure out what to do with the tube of viscous goo at the top of the dam, and wondering how they got a metal grate into the forest floor!
OK, let’s use technical terms here, the “thingie” that appears in the final photo, at the top of the frame, has to have a purpose, but first let’s establish that I’m seeing this correctly. It appears that the sliding window is held in place by a lip, on the inside of the frame, that would prevent the slider itself from being removed, or tilted out of it’s track. Is that correct and does the that lip run from top to bottom? Next question, does the slider go all the way to the top of the frame, or does it stop short, leaving a space between the top of the slider and the top of the frame?
Back to the “thingies”, do they look like they can be flipped out, probably from the bottom? You might need a small intsrument for this, such as a small screwdriver, or a knife. Don’t use took much force, we don’t want to damage anything.
I like mechanical challenges. I know damn well if I were there I could figure this out. Unfortunately I’m clear across the country.
The lip runs all the way up. The window goes almost to the top, but there is a gap. The plastic gizmos stick up higher than the top of the window, and they hit the top of the window frame, causing the gap.
The metal thingies do not appear to move with a moderate amount of prying. I think they may be there to provide a slight catch for the window when it is all the way open, to prevent it from slamming shut just from gravity.
Sounds logical. There’s only one other possibility, that I can think of. You said that, after pulling down on the two pins, that you could get the top of the screen to move in about a half inch. Is it possible that, after doing that, that you could lift the screen frame enough to free it from the lip at the bottom and then pull the bottom toward you, freeing it.
Sorry, but, if that doesn’t work, I think I’m out of ideas.
No, as I said before the amount it tilts forward allows for no vertical movement whatsoever. This was the first thing I tried. Also, the bottom slants up as well as having a lip, meaning that it would have to lift even higher in order to get out.
Two of the pix of the top rail of the bottom sash seem to show a square cap atop each side rail. If these caps will pop off…aw, heck, Opal, I don’t know what happens then.
OK, at this point I think you should go to a bar, pick up a handsome and strong looking fellow and try to kill two birds with one stone.
I’m sorry I couldn’t be of help OC. I hope you figure it out and I’d appreciate it if you’d let me know the solution. Good luck.
I have the same type of sash mechanism in my windows. A.R. Cane is on the right track. The little gray/siver thingie in the right track (pic 11 of 11) is the key to removing the lower sash. There is one on the left side as well. Using a fingernail or butterknife, slide up under the lip at the bottom of it and pull each one toward the center of the window. They pivot from the top and won’t fall out. They should swing out about a half inch or less.
If you look at the top of the sash in pics 9 and 10, you will see plactic inserts sticking up next to the little square caps on each side of said sash. These inserts hold the mechanism that lets the sash operate. Slowly raise the window sash up as far as it will go, passing those thingie that will stop the inserts and free them from the sash. You may feel some resistance as the sash moves in relation to the inserts but soon you will see the inserts start to appear from the bottom of the sash and you can slide one or both out.
Without the insert/s the sash is narrow enough to be removed from the track, giving access to the screen frame.
Reinstall the sash in reverse order.
You might try pulling out just one of the thingies first to see if the sash can be removed by removing just one insert.
Dammit, post 1 page 2 refers to last post page 1.
Now we’re making some progress!! I got to the part where the inserts stick out of the bottom, but I can’t make them slide out. Do they just slide straight down? Should I just get some pliers and pull really hard or what?
(I don’t think I would have ever figured this out on my own btw… how weird is this window?!)
Is Dominic home? I loved the suggestion of letting a kid figure it out in 10 seconds flat! 
Dominic is with his dad for the summer (he splits his summer between his dad and my mom).
Good news! I DID IT!!! I got the damned screen out! Thin Ice’s directions were dead on, though pulling the insert out of the one side required pliers and a fair amount of effort on my part, especially since they’re spring-and-string loaded and connected into all kinds of inner mysterious parts of the window frame that I didn’t bother to examine, what with trying to hold the window up in the air while removing the screen…
I got the window back on, too, which I was a little worried about, but it was actually easier than putting it on, because the string & spring are pulling with you rather than against you.
This is another case where being something slightly taller than 5’2" would have come in handy…
THANK YOU THIN ICE!!!
Do I at least get an “atta’ boy”?
Hope you’ve managed to figure it out.
I wanted to come back and thank everyone for their help, I was rushing to get to an 8:00 karate class so I didn’t get to say everything I wanted to say.
But anyway, thank you to everyone for taking the time to brainstorm and research with me! I really appreciate it, and I really don’t know how I would have finally gotten the damn thing done without your help. MWAH!!!
Glad I could help, OpalCat.
Atta boy, A.R. I mentioned you in post #50.
I saw that, thanks. I’m just glad she finally figured it out. On to the next dragon! 
What I want to know is… WHY? WHY this strange and difficult system? I mean I never would have figured it out on my own, and it’s not like I got “window manuals” when I bought the house… seriously, are people expected to just figure this stuff out? Wouldn’t it have been a million times easier just to make a tiny change to the design of the outside frame so that when you pull down on the pins, you can push the screen outward and remove it? (This is another thing I wanted to get into earlier but was rushing to karate).