I've been struggling lately with the putter and think I've found the culprit. In an attempt at maintaining a light grip pressure on the putter throughout my stroke, I've developed a habit of inconsistent grip pressure. Once I start back, it gets lighter then on the forward stroke, I end up increasing my grip pressure which is leading to poor contact/direction.
I know the greats advocate pretending like the shaft is made of glass but I guess I'm overduing it. It seems I do better when I keep about a 7 (out of 10) amount of grip pressure.