put your finger on
put (one's) finger on (something)
1. To recognize or recall fully, clearly, or correctly. (Usually used in the negative.) I can't put my finger on what this is reminding me of. There's something off about her story, but I can't put my finger on it.
2. To recognize, identify, or determine the fundamental aspects of something. Well, I think you put your finger on it when you brought up the issue of tax increases for lower earners.
put your finger onidentify something exactly.
1988 Glenn Patterson Burning Your Own There was something about the dinette that struck him as peculiar, but he couldn't quite put his finger on it.