Ok, this cannot be difficult, it slid there with the force of gravity right.
You tried everything you know.
So my suggestion now is to get a rigger or an engineering type person to unjam it using his ideas.
A fresh look and attempt should
work. There is no way that it will not slide back up unless it somehow slid over a ridge that stops it sliding back the way it got there.
Please keep us informed with the progress.