Okay, I just went through this headache on mine, so I figured I'd share the love with you guys. There's lots of videos on how to takedown the hammer assembly and the rest of the gun, but this is for the Zastava M57A (7.62x25 Tokarev) [ Pistol M57A | Zastava-arms ] or M70AA (9mm Luger) [ M70AA | Zastava-arms ] handguns made in Serbia starting in probably 2011 or so. They have a thumb safety on the slide itself is the models I am talking about, and when you turn it, I believe it actually blocks the firing pin from the hammer.

Anyway, to get the firing pin out (I had cosmoline or some oil blocking my firing pin, it was nasty, I have a very early manufacture one I believe), I took a piece of steel rod about a foot long and the size of #9 Wire and flattened and smoothed it on a bench grinder. Push in on the firing pin from the rear of the slide until it goes past the slide safety and can go no further.

Now, take a fine tipped vice grips with some cloth or leather on it, and clamp the firing pin right where it exits where is sticking out of the firing pin hole next to the extractor where the shell casings sit.

Now that you've done that, you need to be careful as hell taking the slide safety out, as there is a little ball and spring that will fly the **** out if you don't. I held a cloth over mine to do this, but a gallon ziplock bag may have been better. Just wiggle and pull (if you need extra force, your rod you made to depress the firing pin can be used as a small prying device to get it started moving, but it comes out very easily), and you only need a very tiny distance for the spring and ball to pop out (the things that hold it in F or S mode). Then remove the rest of the way. If it won't come out, odds are your firing pin is not depressed enough, as that is what seems to hold this mechanism in place. If somehow your vice grips slip off and your slide safety isn't completely removed, I recommend you push it in all the way again and start over, to keep from launching your firing pin or getting anything bound up (I had this happen once when using needle nose instead of vice grips, actually).

Okay, now you take your rod and put pressure on the firing pin again. And hold tight because we are going to release the vice grips, and then slowly let pressure off the firing pin with the rod. Then take the firing pin out.

Now clean everything as you will, and we're going to sort of reverse these steps to go back together.

Put the firing pin in, compress it fully with the rod and then use your vice grips (with a cloth or leather) to hold it.

Now, put the slide safety back in, but stop a little shy of all the way so you can deal with the ball and spring that must fit into the detent. I had mine angled down towards S and found it was easier to install that way. Then take a needle nose pliers, and take the slide safety, install the spring, put the ball on the end, and compress it (very little force required, but hold tight). Now put the slide safety down as far as it will go and ease up tension on your needle nose as you push down and hopefully it snaps into place and the ball and spring doesn't take off flying around the room until you order new parts from Sarco or somewhere or make your own.

Now, rotate the slide safety to F and use your rod on the firing pin so we can release the vice grips and then let it come back all the way. Tada, we did it! Don't ask me how long it took me to fight through this for the first time on my own, but there isn't a lot of information on this particular variant, so hopefully this thread can help somebody out.