I came across this:
OopFactory X12 Parser - https://x12parser.codeplex.com/releases/view/106524
Incredible. Source code was well structured, everything built on first open, even had unit tests.
Pulled into my project, it converted all the files I tried.
It includes a command line exe which worked - but as a .Net guy the library was really impressive.
-Update-
The short short version comes down to something like this:
var fstream = new FileStream(fileName, FileMode.Open, FileAccess.Read);
var parser = new X12Parser();
var interchange = parser.ParseMultiple(fstream).First();
var x12Xml = interchange.Serialize();
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…