If we're to do anything, we have to put our fingers on the cause.
He couldn't quite put his finger on what was wrong.
And then she put her finger on the other one.
But what they were she could not quite put her finger on.
Of course, he shouldn't be able to put his finger on anything.
Here she has put her finger on a truth of human nature.
Something was very wrong here, but he couldn't put his finger on what.
And something else she couldn't quite put her finger on.
I'm just trying to put my finger on the problem.
I'm not sure I can put my finger on them all.