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