The 28-year-old hitman played a huge role in helping the Magpies win promotion to the Premier League last season by netting over 20 Championship goals.
But the Newcastle man has struggled on his return to the top flight, netting only three goals in 15 league appearances this season - and all three have come in his last six games
Gayle, who joined from Crystal Palace for £10 million 18 months ago, has only managed 18 Premier League goals in 79 games for United and the Eagles.
And with Rafael Benitez's side languishing in 18th spot, club legend Dyer feels that the Spaniard needs to sign a proven goalscorer.
“I think they need a goalscorer - someone who is proven in the Premier League or in a top league to score 20 goals a season,” he told The Chronicle.
“Dwight Gayle has probably been the shining light and he scored goals in the Championship but when he’s been in the Premier League before he hasn’t really set the world alight.
"The centre forward is the one area.”
It's perhaps indicative of Newcastle's less-than-impressive striking options that Gayle has even played as many as 15 games.
His only competition is Joselu, who has bagged three in 16 outings following his £5 million summer move from Stoke City, while Aleksandar Mitrovic has one goal in less than 90 minutes of Premier League football all season after falling out of favour under Benitez.
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