At the start of this winter season, I was putting really well. Over the past few weeks, playing the same courses, my putting has been poor. I haven't changed anything I'm aware of; still use the same grip/stroke, routine, ball line mark, etc. The only thing that has changed recently is my new/used driver - which has been helping my score. Maybe I've been focusing so much on driving the ball that I'm subconsciously not focusing enough on my putting. Then again, perhaps there is simply a greater power that only allows all parts of the game to stay in harmony only every so often.
The only tip I can offer is a routine I practice on the practice greens. I lag 3-4 balls from about 20' then putt all from the ball furthest out. I repeat that for any not made on the 2nd putt. Because I hate leaving those 2-3' "knee knockers", it seems to help me focus on not leaving any outside that range.