JamesH:

(Just noticed you are a lefty...just keep in mind my reply is for righties so reverse the terms to apply to your side of the ball....)

For what it is worth, you may want to take a look at a post I sent earlier today concerning "spine tilt" that is in the "maintaining spine angle thread" on this page. It should be the last post in that thread as it just was sent.

Your problem you describe hitting the fairway woods and hybrids fat and thin sounds just like what I was dealing with recently. I corrected it with a simple adjustment at set-up called spine tilt (created by the right shoulder being lower than the left because the right hand is lower than the left on the grip) that is critical to being able to get and stay behind the ball on full shots. This tilt allows you to do so without needing to move off the ball with a drastic weight shift. These shots are difficult anyway because they require a good deal of precision with the strike as well as speed and power. You want to be able to keep the body as steady as possible to accomplish this. The correct set-up including the spine tilt away from the target may help. Check it out next time you go to the range. With the tilt, your head will be a few inches behind the ball at set up. The ball should be roughly in line with your left heel if you are a right handed player.

Good luck