Somebody that knows electronics, simple Q

[Mantis]

The LED on the battery charger for my E-Mag doesn't light up anymore. I think it just may be the LED rather than the whole charger that has failed. I imagine there is a way to test this with a voltmeter, but I'm not sure how. Can somebody please tell me the specific settings to turn the voltmeter to and what parts to tap with the probes? Oh, and what reading means the charger is working.
Thanks

[sicones]

set the meter to DC and expose the positive and negitave leads and probe + to + and - to -

red=positive
black=negative