just an update
I had a 580 thats about 2 yrs old that was going into TTL and it would not flash at times. TTL mode situation was random, no flash sitiuation happened every 100 pops or so and then would clear up for a few hundred shots.
turned out to be a bad reflector assembly. cosy me 98.69 to get it fixed. i thought that was very reasonable . i know a couple others mentioned they had similar problems. thought you should know
