Over 20 years ago, when I was still a brand new, shiny, baby Trooper, all full of good intentions and the belief all people were fundamentally good and decent, I bought the largest D cell Mag lite I could find. Over the years both the flashlite and I took a lot of abuse. It eventually came to be known affectionately as "Thumper" and it served flawlessly and saved my bacon several times. The poor old thing (the flashlite, not me) eventually quit working. The other day I disassembled the unit, having to resort to a large set of Channel Locks and a pipe vise, and went at it with abrasives to remove a couple decades of oxidation and corrosion. As with any electrical device, grounds are key! I'm happy to say Thumper is back in working form and ready to give years more service. It's like having an old friend back.