I am installing a 3-1/4" x 3/4" hardwood strip floor. I've found that in some cases the ends of the boards leave a small gap that we didn't force together properly. How should I fill those gaps. Also, where the rows came close to the walls and I couldn't use the power pneu nailer, I had to nail them through the face of the boards. How can I repair the tops of those nail holes?