How to test my 420EX?? Or is it junk.....

Have a 420 that has been used maybe 100 times (mostly on my G6) but on my 30D it works maybe 1 out of 10 times?
Is there any settings I can use to test this flash, so I know if I need to toss it?
TIA,
cntry

I know this sounds really simple, and you have probably done this, but change the batteries. Have you been trying to use it outside in the cold? That really kills the batteries quick. If you have fired the flash repeatedly for a long time that can wear out the bulb.

Take it to a repair place, other than that my suggestion would be to get a 580EX if it is in your budget, it is a great flash with a lot of useful settings and lots of power.

Make sure the contacts are clean, too.
If you can't make it work on your camera, try it on someone else's camera.

Batteries huh.........

Any luck? Just curious - cause I know this real loser photog - down the way, he ah...didn't put any batteries in at all!!! Boy did I - ahem...I mean: did HE feel stupid!!!?

Yeah batteries make alot of difference.