580 EX not firing ??

I've done a bunch of oogling, and while there are a lot of hits for 580 EX not firing, they don't quite answer my question. Hoping someone here may have some experience with this. I bought a 580 EX years ago used, and never quite figured out how to get the results I wanted from it--so it sat in my bag (I'm not convinced it worked properly to begin with). I just pulled it out, put fresh batteries in, and started playing with it. The pilot light turns on, all the function buttons appear to work, but it won't flash. It won't even test flash when I hit the pilot button (not mounted to camera).

Anyone hear of this?

I checked the repair quote on Canon's website and it looks like it could cost $190 plus shipping... seems a bit prohibitive. I may as well buy a new flash. :(

Busted bulb?

Dunno, how would you check that?

Anyone ever send a Speedlite into Canon for repair?

Finally got around to figuring out how to pull this apart. Sure enough, busted bulb.