Chester looked unlikely to get back into the game, although John Welsh hit a shot narrowly past the post on ten minutes and Paul Linwood headed a good opportunity straight into the arms of keeper Andy Warrington.
It was a scrappy stop-start affair in the first half, with the referee's whistle playing as big a part in the game as the players themselves with infringement after infringement, the majority of which seems to be shared between Kevin Ellison and Dale Tonge, who both went into the notebook after a succession of fouls.
Deep into first-half added time Chester captain Paul Butler produced a brilliant block to deny Danny Harrison's seemingly goalbound shot.
The visitors should have doubled their advantage on 63 minutes when Pablo Mills rolled the ball across the face of goal where O'Grady came sliding in, but he could only direct the ball wide when it looked easier to score.
Ten minutes from time sub Jamie Yates saw an effort saved by Danby and Chester defender James Vaughan almost inadvertently deflected the rebound into the net, but it rebounded back off the post and he was able to clear at the second attempt.