I'm at ef details as well. I would soak it in acetone, then verdicare. It will always be splochy but the conservation will at least minimize any problems, and lets face it, the corrosion is on the reverse; which also minimize the damage. As to value, I'm not sure. It is a tough one to find. $30 to $45 I think is a fair range. Believe it or not, nano technology will probably be able to fix that in 30 to 40 years...or less. I'm a retired Engineer. This is going to be an interesting hobby when that tech is widely available.