Find Detector

At the point of finding the hole to knock down the bridge support but can't find the hole area. Where can I find or refind the detector. I have the hammer / pick axe and the lighter,,,nothing seems to help here.

Not a bad game, like the search item in the tools....about the only way to find some of the items\

let me clarify detector,,,the thing that works like an exray machine . Thought that might help get an answer...