are these screen thing adjustable? replaceable?

thanks

Aren't those just spring-loaded plungers that engage in holes in the window frame proper to secure the screen in place? If you pull all of them down/out at the same time, you should be able to remove the screen unit from the window (at least if the window is open). If they are the plunger thingies, you might well be able to get replacement parts at a HD/Lowes, though that would only help the rattle if they're actually broken.