I agree with you davbrucas, I previously played a straight draw, or a pull draw (closer to a hook) for some time, thinking that all i needed to do to fix the problem was to push my arms out, or away from my body to give the draw a nice push. After a lesson from a very reputable coach, he noted: in summary, that my arms were beating my hips and shoulders through. What I have done to improve this was a combination of two things.
First: bring your club to its peak backswing, pause, and than yank the leading hip back, as if someone grabbed that pocked and pulled very hard from behind you, you'll notice your arms will begin to drop as well. Make not of this feeling as it is how your downswing should always start. Something to think about is that to start your downswing you are squashing a bug with your leading heel. A good drill for this is to put a medicine ball between a wall and your butt ox, than do an easy swing, the medicine ball should not fall to the ground until about three quarters or more into your follow through, this insures your butt ox isn's shooting forward before impact (in other words your standing up early to compensate for going off swing plane because of the arms taking over).
Second: This is in addition to the firing of your left hip backward. As stated before you'll feel your arms drop when your left hip begins its rotation, at this point you will want to take your back shoulder and push that through the ball while keeping your leading arm straight, do this without breaking your wrists. Note your head should not be moving in front of the golf ball until 3 quarters up your follow through, and your right shoulder is rotating with the grip of your club going from the rear side of your body to the front (the follow through side). Its is as if your grip is in a race with the club head, and you need to make sure than while only using your shoulders (again I cant enforce enough that your head needs to remain behind the ball while doing this) the grip wins this race.
In summary: squash a bug with your leading heal at the beginning of your downswing, keep your butt from shooting forward. And than to ensure you get the torque and not block the shot push your rear shoulder around, like your trying to hit the ball with this right shoulder. Then when you made a normal swing your arms will be in tune with your hips and shoulders without thought.
I hope this helps, I tried to be as clear as possible, its a little tough to explain