Was nothing.
I think your problem may be similar to the one shown in this video:
<iframe width="560" height="315" src="
https://www.youtube.com/embed/Ycd_FM7ztgM" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
Maybe you've already seen it... but here's a video and an article with photos about the frame where you can see some details:
<iframe width="560" height="315" src="
https://www.youtube.com/embed/uVw6SkikQmY" title="YouTube video player" frameborder="0" allow="accelerometer; autoplay; clipboard-write; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe>
https://alibuy.biz/2022/01/03/fm-fs831/ In the video I think they speak in Russian, and you may have no idea what they say, like me... but the article, which is in Ukrainian, you can translate it with your computer/smartphone.
I have my frame completely disassembled and still unpainted, I have stopped the project to wait for the JJJ screws (thank you by the way JJJ!, they are very good) or the new rear triangle, which I have decided to order and have also received a few days ago; if you or someone else wants a detailed photo of a specific piece, I can do it.
I'm a bit busy right now, but I hope to take it to paint soon and finally assemble everything. Greetings.