Originally Posted by DustyDisks
Just a small warning, if you use anything metal to "poke" into the plug end of the charger
otherwise known as a "wall wart" you run the risk of blowing the fuse that is sealed in the charger and generally it is non-replaceable for most people.
If any probing is done make sure everything is unplugged from the wall/mains, so you do not damage the power supply.
Your advice is good as far as it goes and only applies if the metal object shorts together both the inner connector and outer barrel. In fact, here in our workshop we have several extensions, made from parts of paper clips, that fit on multimeter probes just for measuring voltage supplied by power supplies with concentric plugs - saves having to get a power socket from the parts department.