...
my $state="outside";
my @servicelines;
my $desc_flag; #is 1 if description found
while ($line = <TEXT_FILE>) {

  if ($state eq "outside") {
    print MYFILE $line;
    if ($line=~/^\s*define service/) {
      $state="inside";
      @servicelines=(); $desc_flag=0;
    }
  }
  else if ($state eq "inside") {
    if ($line=~/^\s*}/) {
      @servicelines= removesam(@servicelines) if ($desc_flag);
      print @servicelines;
      print $line;
      $state="outside";
    }
    elsif ($line=~/^\s*service_description/) {
      push @servicelines, $line;
      $desc_flag=1;
    }
    else {
      push @servicelines, $line;
    }
  }
}
...