A cheap but invaluable tool to have in your Box is a 3.5mm Back box re-threader or a (Tap as they are usually called) you can pick them up for about 2/3 quid on Ebay/Amazon, for those rare times you wear out a thread When 2nd fixing especially if you have to use the Long screws ,also pick up a 4mm Tap just incase you can't re-thread with a 3.5mm ,it will save you a lot of Time & Hassle than having to replace the Box or if you can't remove the box it will save you from Having to drill through the back of the box so you can tighten up the screw so the Socket/Switch plate is secure enough not to move