Help with stairs

[lundmarx]

Hello!
I really need help on how to go about fixing our staircase.
It's an old staircase where the steps have slid out of the stringer. The staircase is U-shaped, and it's on the outer edge of the middle section that they've come loose. Steps 5, 6, and 7 are the worst; those steps wobble a bit when you walk on them.
I've been thinking about possibly screwing some brackets onto the stringer and into the "center post" and then trying to pull it together with the help of a wire.
I would be very grateful if someone knew how to proceed.
Best regards, Johan
Attaching some pictures of the problem.

 

[Åsa Lund]

Can you access the underside of the steps so you can screw sturdy blocks in place for the steps to rest on?

 

[lundmarx]

Thank you, Åsa, for your response.
I actually did that, so they don't fall down at least. But I would still need to tighten it somehow as the gaps are so large that you can see between them.

 

[Åsa Lund]

Can you spread glue in the gaps and then brace/prop with a board against the opposite wall and push the ladder sideways back to its old place?

 

[lundmarx]

No unfortunately. It seems like you have to press the side rail against the ladder and you can't reach there because it sits flush against the wall.

 

[Åsa Lund]

I meant if you aimed on the outside of the staircase towards the wall on the other side in the stairwell? It's a bit hard to see in the pictures, but I thought it might be possible. Otherwise, call a stair carpenter company and ask for tips, should be eligible as ROT?