Dumb question, but did you pull the 3055 to test it? You will get false readings if you try to test it in-circuit. (It's also possible you're being tricked by some other component, if you measured those in-circuit as well. You'll think it's ok, but maybe it's just looking that way, because of something else in the circuit.)
If you think you've checked everything, and it's still not working, you're basically in the 'question all of your assumptions' mode of troubleshooting.
I suppose a shorted cap maybe could mess things up, but I can't say I've seen one, and you should be able to test that with your DMM pretty easily. Ideally, you should have a cap meter, and lift one leg of each cap to test it. Also, a cracked resistor could maybe do the same. I sometimes will push on each resistor (and the glass caps too, if you have them), to make sure they're solid. If they're cracked, they'll usually break apart.
Also, I don't know if I mentioned this before, but test the pins in the connectors for continuity. I've had a couple where the pins broke inside the housing, near the base, so they didn't pull out, but they weren't making contact.
If all else fails, send it in. I'll figure it out for ya, for the price of shipping.