Tim Webster has quit Buxton and will be replaced by Adam McKinna.
Webster said he did not want to let the club down as he was struggling at the Hi-Edge Raceway and will now pursue other options.
McKinna returns to The Hitmen having previously raced for the National League side in 2008.
"Obviously it has left a hole in the team as Tim was the second highest averaged rider," Buxton chief Jayne Moss said:
"Adam has had an unlucky couple of years, he has suffered a lot of injuries which has kept him out of team plans on several occasions.
"But when he's raced he has been a high scorer in both the National League and Premier League for Newcastle."