Anyone out there know how to dissolve cured epoxy?? Is it even possible?

Not tht I have ever come across. Heat will soften it enough to get it off some things. Where have you got it that you don't want it?

poured 3/8" thick between two formers on the inside of the balsa skin to reinforce a fracture. Now the darn servos won't fit. They bottom out before they sit on the rails. I guess I'll have to carve it out. Maybe I'll use the tip of my soldering gun.

The soldering gun idea will work but your ventilation has to be excellent. I would even say doing this task outside to be the best. I have also had success using a Dremel to remove epoxy. Anything that could dissolve epoxy would probably be hazardous to your health. Good luck.

If it is just barley hitting (bottoming out the servos) maybe laminate a thin piece of ply ( 1/16" or 1/8" ) on top the servo rails.

Rotary tool (i.e. Dremel or similar) with cutting bit works good. You can just grind away the epoxy. In the future I'd suggest not casting pure epoxy for reinforcement. There are better (lighter and stronger) ways to use epoxy, such as using fibreglass/epoxy or mixing strength fillers in the epoxy, such as micro fibers. Cheers.

Thanks, Tom.

Guy,
I tried that but the wing won't fully sit in the saddle.

Tom,
you're right of course. I was just being lazy. See, I'm always fighting a battle against time. I can only work on my stuff between 4am and 5:30am. The rest of the day is shot and my weekend are spent catching up.