Finn has had two international wickets chalked off when the umpire deemed him to have disturbed the bails at the non-striking end during his delivery stride.
The paceman has been working on the issue with England bowling coach David Saker.
"It's getting there," BBC Sport quotes Finn as saying. "Every day in training I'm working hard on trying to eradicate it. I have been for the last four months.
"It's something that's obviously going to have to improve, and it is. I'm trying different things, and out in the game it's not happening as frequently as it used to.
"So I hope there will be a stage where it's completely eradicated."
England face New Zealand in the final match of their Twenty20 series on Friday.