I did a SAO conversion and am having trouble getting the right side safety back in.  If I don't have the sear cage in then I can get the two safetys to mate up in the frame but once I drop the sear cage in and I get the left side safety under the leg of the the spring in the sear cage then I can't get the right side safety flush.  If I back out the left side safety a bit then I can get the right side safety in but then I can't get the left side safety in enough to pull the detent back and click both sides all the way in.

I watched this guy's video and he was able to get the left side safety 90% in and then just drop the right side safety in without any effort. I wonder if it's something to do with the alignment of the sear cage?  There's a small metal piece (Safety detent plunger) that sticks out on the left side of the hole for the right hand side safety and I think it's not able to clear that piece.  The only way I can pop the right side safety in is to point it up to the sky first and then rotate it down into a horizontal position.  I have no idea how he was able to just push the right side safety in horizontally.

https://www.youtube.com/watch?v=U6hkoA1kfnw&t=26s

I was able to get the two sides to mate up now so that when i move one side up the other side moves with it but when I use a pick and pull back on the left side plunger I can't snap the last bit of the left side in.

Got it all back together.  I think the positioning of the sear cage is key and for me I had to put the right side safety in first and then work the left side in after. The hammer had to be uncocked as well.  Not a fun job

there is a detent thingie on that side.

I just take out the sear cage and remove the detent. Install safety and insert detent.

much less frustration doing it that way.

Which side, left side or right side?  They both have a detent, the right side one doesn't have a spring, the left side one has a spring with a plastic detent.  How can you install the safety without the sear cage in?  You can't install the detent once the sear cage is in either.

I think there's two or three different types of safeties on the CZ75 types.

If your right side safety has the detent, but not a spring to force if forward, take look at the safety where it sticks through the frame.  The "ring" may not be round.  It may have a sort of flat side.  If it does, put the right side in first, turning the safety so that it slides fully into the frame, then let it rotate down and you'll see that detent in the frame fits into the slot between that inner ring and the safety shaft.  That is what holds those safeties in place.

If that is what you have and it works you'll be ready to put the left side safety in.

Yeah, you've gotta get the left side safety shaft to go under the spring in the sear cage first.  Push it in as far as it will go (don't force it).  It will stay in place while you do the next step.

I use a small pick/hook to pull and hold the detent to the rear (it's got those two little teeth sticking up for the tip of the pick to fit in while you pull it back.)  At this point you've got to line up the right side and left side safeties so the left side safety shaft goes into the right side safety correctly so using either one rotates the left side safety shaft.

I'm not sure which one is best (or worst) to work on.  The models that have springs on both sides or the ones that have a spring on the left side of the frame only.

Good luck with it.

I was a bit nervous about taking my SP01 apart to do the SAO conversion but it didn't fight me too much. That said, the right-side safety and trigger return spring were absolutely miserable to get in. Those two items took longer than everything else combined

You nailed it had to do the right side first and get it in by putting it in facing up and then rotating it down to get it past the detent.  The left side took several tries and lots of cursing to get it lined up just right to get the two sides lined up and several more tries to get the detent on the left side back and the left side popped all the way in.

talking about the detent.

the right side safety has a hard time going in with the detent (rt side) installed.

remove sear cage
remove rt detent
install rt safety
install rt detent
install searcage
install left safety

The left side needs to be pushed back with a pick before the safety (left) will go all the way in