Sorry for the late reply. I like your idea of a regex.

use warnings;
use strict;

while (<DATA>) {
    print "$1 $2 $3\n" if /^\s*(\d+)\s+\S+\s+(\d+)\s+\S+\s+(\w+|\w+\s\
+w+)\s*$/;
}

__DATA__
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Information Summary for Head #1, Site1:
  No.            P       Device          Percent     Name
 -----------    ---     ------------    -------     -----------------
     1           F        14             0.06      OPEN
     2           F        216            0.97      CONTACT
     4           F        326            1.47      LEFT
     5           F        232            1.05      MID
     6           F        54             0.24      RIGHT
     7           F        6              0.03      AT
     8           F        6              0.03      AT_GHT
     11          F        184            0.83      5DBLT
     12          F        151            0.68      2P5D
     21          P        21009          94.64     Bin P

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