Mine is working, so I'm not taking it apart, and without a photo, I'm not real sure what the "little green ball" might be. However, tantalum capacitors frequently look like little balls with two metal leads. If you guys would post clear, closeup pictures of both sides of the board, I'd be willing to make a schematic and offer suggestions for alternative components.
As I read the thread, I was thinking that the most difficult part would be to identify any integrated circuits (although I suspected it'd just be an opamp), but thankfully jshadows did that. Now that we know the main circuit, the rest should be pretty easy.
By the way, the
LM1815N is just under $4 at Digi-Key (over 600 in stock) and
here is the datasheet.