From what you are describing, the fastener circled has play? or that it is not retained from above? It has been a while since I have had one of these in my hand but the nose has a bolt that can be adjusted for additional tension, which I would think would help, but if you have run out of threading (your red circle hides things a bit) that might be a problem. The flanks appear a bit splayed out those can be brought in which might help the cause and or make the saddle more comfortable.
The nose bolt if I remember correctly is kind of a threaded stud that took a square socket, access from inside the saddle.