Tim Southee admits he has bowling technique issues at test level and has vowed to put them right.
Ineffectual against South Africa in the drawn first test, Southee was dropped for the remainder of the series - making way for a recall for Wellington paceman Mark Gillespie.
Southee told LiveSport he was relatively happy with his form in the Twenty20 and one-day series against the Proteas but acknowledged he had been struggling in the longer form of the game.
"It's just about keeping the front arm up higher and for longer then finishing off my action right through and a lot harder and getting the bounce back off the wicket," he said.
"In the last couple of test matches because I've been rolling out of the action so quickly the ball's been going along the wicket rather than into the wicket and it's a lot easier to face for the batsman if the ball is going along the wicket."
Southee will play for Northern Districts in the Plunket Shield on Sunday and is positive his form will come right.
"I'm just going through a little period where things aren't going as well as I'd like them to go...I've only got myself to blame."
Black Caps coach John Wright was confident Southee would bounce back from his disappointing form.
"He's doing what we call coming out of his action too early which is a technical thing. It may take a little while to sort out and it's a bit like a batter out of form," Wright said.
"He's a little bit low on confidence because it's not for a lack of trying. We've given him a few things to work on and he'll be back at some stage."
Was a life ban from cricket a fair punishment for Lou Vincent?Related story: (See story)