Golay correction not working as expected

[colinbrislawn]

Here is what forum user dfground found in forum x-ref.

barcode-uncorrected 1 (GTA TTT ACG ATC) and
barcode-uncorrected 2 (GTA TTA ACG ATC) have been corrected to
barcode unused index (GTA TTG ACG GTC) by golay-error-correction.

barcode-uncorrected 1 GTATTTACGATC
unused index 1        GTATTGACGGTC
                      ***** ***.**

barcode-uncorrected 2 GTATTAACGATC
unused index 2        GTATTGACGGTC
                      *****.***.**

Both barcode-uncorrected 1 and barcode-uncorrected 2 were thought to be caused by the insertion of a single base into used index 1 (GTA TTA CGA TCC).

barcode-uncorrected 1 GTATTTACGATC-
used index 1          GTATT-ACGATCC
                      ***** ******

barcode-uncorrected 2 GTATTAACGATC-
used index 1          GTATTA-CGATCC
                      ****** *****