The dream team could not produce a dream start to their return to Vale despite Tom Pope getting on the scoresheet.
The return of Neil Aspin and John Rudge was greeted with delight by the Vale fans but a poor second-half performance saw the Valiants fail to secure a first home league win of the season.
Aspin’s formation perhaps showed Vale’s limitations with wingers Marcus Harness and Ben Whitfield supporting lone striker Tom Pope.
Vale showed flashes in the first-half with James Gibbons and Tyler Denton having bags of energy on the flanks and Whitfield missing a good chance. The Vale goal came in the 39th minute when the Grimsby keeper failed to gather the ball and Pope fired home.
However, it was different story in the second period with the diminutive Dembele increasingly to the fore for the visitors. First, Sam Jones, ironically a player Neil Aspin developed and sold on at Gateshead, nodded the visitors level on 51 minutes and then Dembele weaved through to put Grimsby in charge on 67 minutes.
Vale huffed and puffed bringing on Dan Turner and David Worrall to support Pope but Vale’s lack of cutting edge was clear as Aspin’s debut ended in defeat rather than triumph.
Vale: Roos, Gibbons, Smith, Kay, Gunning, Denton, Tonge (Turner), Pugh, Whitfield (Worrall), Harness (De Freitas), Pope
Subs: Hornby, Barnett, Davis, Anderson