You are downloading, not posting.
That aside, take a close look at the files from MC and your manual program.
Is there a % or some other character at the beginning or end?
An NC file is an ASCII text file. If you had it in Notepad the format should be correct.
The one line transfer is a hint. At the end of line, the Carraige Return - Line Feed (CR-LF) character may be different between MC and Notepad. CR-LF is terminology that dates to the teletype terminals used yeears ago. You see it as a new line of code starting at the first column. The control interprets this character as an End Of Block (EOB) character. Copy a couple lines from the MC program and stick them at the top, then edit them to look like your program without changing the CR-LF and see if that helps. There may be settings in the DNC portion of MC that is using a different character.
You could use Hyperterminal which (I think) is part of DOS or your Windows operating system to transfer programs. Otherwise download a demo version of DNC software, like Multi-DNC which you can use free for 30 days. Multi-DNC that I used only counted down while the software was running so potentially could be used quite awhile as long as you only keep it open for the download or upload.