The NEC1 .IRP should be,
"Function=0..255" will generate all 256 possible codes for that Device No.. If you only what to generate OBC 1 you would enter "Function=1" (without quotes). See the ReadMe file in MakeHex for more info.
The EFC No. is not needed for MakeHex.
Even though your learnt code has a Frequency of 51175 Hz (may have been a bad learn) I would try them at the default 38000 Hz which is NEC1 protocol standard Frequency.
Using the MakeHex GUI with MakeHex makes it alot easier to use. You can also use IR Panels to generate a CCF file from the .HEX files from MakeHex but the "OUTPUT!" must be set to Decimal.
Place in the same folder as Makehex.[Link: files.remotecentral.com]
CCF Panels (IR Panels)
Generate a CCF file from the HEX file created with MakeHex.
After creating a HEX file, open it with a text editor such as NotePad. Use "Edit" "Select All" (or Ctrl +A), then "Edit" "Copy" (or Ctrl +C) to copy all the text. Then start IrPanels and use Ctrl +V to paste the text into its window and press Generate CCF File. A CCF file will be created in the IR Panels Folder called IRCodesCreate (Don`t use the file called IRCodes Master) that you can use for testing in a Pronto Remote and some others.[Link: files.remotecentral.com]