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Dartford suffered a sixth straight defeat on Saturday and had Lee Noble (pictured) sent off for violent conduct.
Manager Tony Burman handed debuts to his two new loan signings, goalkeeper Phil Smith and defender Connor Essam, while Elliot Bradbrook returned after injury.
Gateshead went close to an opener when Josh Walker headed wide from Colin Larkin's cross.
At the other end, Adam Birchall chipped a shot just past the post and then forced Heed keeper Adam Bartlett into a good save.
But the Darts were reduced to 10 men after the break when midfielder Noble was adjudged to have deliberately elbowed Jamie Chandler.
However, it looked as though the hosts had done enough to stop their losing run, until Lewis Sirrell crossed for substitute James Brown to score in the 89th minute.
Dartford remain 22nd in the Skrill Premier, two points from safety.