Hey guys.  I have an issue with a set of Binos that I need help with. 
I have a set of Nikon prostaff 3s. The issue is that they don’t stay “spread out”
If I spread the tubes out to match my face, they will slowly collapse back together. What is the fix for this?
It’s hard to describe so I will show pics.
How it starts,

How it ends up.

And the model info.

Thanks. I’m not well educated on Binos, so I really appreciate any help.
Thanks.
 I have a set of Nikon prostaff 3s. The issue is that they don’t stay “spread out”
If I spread the tubes out to match my face, they will slowly collapse back together. What is the fix for this?
It’s hard to describe so I will show pics.
How it starts,

How it ends up.

And the model info.

Thanks. I’m not well educated on Binos, so I really appreciate any help.
Thanks.