If you have ever suffered from the putting yips, you know just how embarrassing and difficult such a simple act like a three foot can be. You would also be aware of how difficult it is to get your putting stroke back on track. I had them once, and it took ages to rid my stroke of them. Here is one drill I employed which really helped.
When I was yipping, it was my trailing or right hand that was doing all the damage. I would twitch at the last second before impact and throw my ball way off line. I also noticed that when I yipped, I was guiding the stroke with my right hand.
To fix it, I worked on this drill to take my right arm completely out of the equation. I started by hitting balls only with my lead hand on the putter. Then I slowly started using my right hand on the putter again, however, my stroke was predominately controlled by the lead hand. When I setup, I felt as though there was a straight line up the shaft of my putter through my arm and to my shoulder. This line remained intact and controlled the entire stroke. I tried to feel as though the back of my lead wrist was aimed at the target the entire time throughout my stroke.
Include this drill, with proper fundamentals and you should be able to cure yourself of your putting yips.