A 2-1 defeat at fellow strugglers Gillingham saw the Kent side leapfrog Blackpool and push the Seasiders in to the relegation zone.
It all started so brightly for Blackpool when Armstrong, in an unaccustomed role on the left-hand side of midfield, fed John Murphy who teed up Parker to put Blackpool ahead after 22 minutes.
But Gillingham, who have struggled under new boss Neale Cooper, almost equalised through former Pool loan midfielder, Michael Flynn. Experienced striker, Neil Harris, also went close.
The inevitable equaliser came jut three minutes after the break when defender Chris Hope nodded home an Andy Hessenthaler cross after being left unattended in the area.
The winner came 20 minutes later when Harris took advantage of an uncharacteristic error by Peter Clarke to nip in and score from close range.
Parker, back after injury, earned himself a needless red card with 14 minutes left.
The result leaves Colin Hendry's side without a win from a dismal October.
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