Green Woodpecker location? Willow Tit nest?

Liz Just wondered whereabouts east of Tregaron you've heard the Woodpecker. In Cwm Berwyn somewhere? This morning I watched what appeared to be a pair of Willow Tits frantically excavating a nest site in a rotten tree very near the beginning of the boardwalk at Cors Caron. Since they didn't call I wasn't 100% sure of the id.