If you have ever tried to get a bulb in or out of back up lt, park lt or marker light you know what a pain that can be, getting the spring on the contact moving properly. In the past I spent what seemed like hours working them up and down with WD40 ect. The other day I was moving a old socket in to a new back up housing and noticed that the contact springs were stuck. I put it in my Evapro Rust tank and in two day it works perfectly. I hope this helps someone else. Marty