Take your pointer finger and thumb, pinch and hold the side of your cheek and then proceed to pull your cheek out and in rapidly. It's call hot dog in a hall wall syndrome or "shaft play".


Ok but in all seriousness, a pinging sound is an easy way to identify if there is a lot of shaft play without actually going in depth and looking at it. It's obviously caused from the blades hitting the housing. At that point, it's normally too late to salvage.