What is a Manc accent? They got away with using mainly Yorkshire born and bred actors in Corrers for years and nobody noticed.
Manchester has several accents as far as I can tell.
I'm from Wythenshawe, Stockport is only four miles away but their accent is totally different. You can already hear a sort of Yorkshire twang drifting in and they have their own terminology for things. I always remember a kid saying to his mum, "Am plairn up brew, ont croft." (I'm playing up the hill on the field....Apparently) I didn't have a fucking clue what he said. That was in Edgeley. I can walk there in an hour.
I have family in Gorton, Openshawe, and Bradford areas who markedly talk differently to us down here. Some Manc accents bare no resemblance to each other whatsoever to my ears at least.