Let me assume a return.

Do you want error checks? Let me assume yes.

Here's an ugly solution. Save this to a file named, say, fixup and then "perl fixup in > out". In case it does not work, do NOT try to edit in place. (Right now you have one problem, you do not want two...)
\n#! /usr/bin/perl -w\nuse strict;\n\nwhile (<>) {\n  if (length($_) < 101) {\n    if (20 < length($_) and length($_) < 22) {\n      # Join the next line on, then replace bytes 20, 21.\n      $_ .= <>;\n      substr($_, 19, 2, "  ");\n    }\n    else {\n      print STDERR "Unexpected return at line $. not in bytes 20 or 21???\\n";\n    }\n  }\n  if (length($_) <> 101) {\n    print STDERR "Line $. is not of length 101?\\n";\n  }\n  print $_;\n}\n


Ben