Harrington has put new grips on his clubs: "I used to have a reminder in my grips, which allowed me put my hands in the same place on the club without looking. Now I've gone to plain round grips and it's a big, big change."
"I was doing a lot of regripping and at times found it very distracting. Now I must look at the head of the club and square the face up when I put my grip on. When I do that, I don't feel the need to regrip."
"I've knocked all the clubs a degree flat. That's a little change. Other small alterations include weakening my grip, lowering my hands a bit at address and pushing them a bit forward."
He has eliminated "two big waggles" with the club standing over the ball: "Sometimes they'd cause the club to twist in my hand. I also looked up quite a lot with my body when doing them, so I lost my alignment and then occasionally got distracted by how the club face was sitting behind the ball."
Harrington has changed his swing trigger: "I used to take the club away from a moving position (his swing used be set in train by the rotation of his left hip as he dropped into a slightly compressed stance). Now I start from a static position, taking the club away first with my arms.
"Changing the trigger is massive but by doing so (and dumping those waggles), I've taken out three things that distracted me a lot. Though my posture looked good standing over the ball, once I started my backswing it was poor because the big movement by my hips put them out of place.
The plane of Harrington's backswing has changed and it's shorter now: "There's more coil in it but it's not as long in terms of my hips and leg action.
"I also have less lateral movement in my backswing and downswing now.
"I'm tucking my head in at the top of the backswing. I used to try and swing my shoulder under my chin, so I'd poke my head out to do it, which I think contributed to issues I've had with my neck."
"I'm going back to squatting quite a bit at the start of my downswing." (All the greats, from Hogan to Woods, initiate the downswing by dropping into a deep, compressed stance, from which they thrust up through impact).
"I'm also going back to getting my chest down more and getting my hands lower through impact. I'm also reducing lateral movement through impact."
"I've changed my (pre) putting routine. Instead of standing off the ball to take my practice putts, I now lift the putter and do them directly over the ball. By taking the putter inside to try a practice putt, I shifted my eye-line, so my practice putts weren't the same as the putts I actually had."