I had a horrible stretch of about 6 months (!!!!!!!!!!!!!!!!!!!!!!!) where I was hitting the ball well in off of the heel. Not every shot was a hosel shot, but some were.
The worst thing was the huge loss in distance, and inaccuracy in distance. I'm not a long hitter, but can put it out there 260-275 pretty regularly. On one hole (in a tournament), I hit my tee shot into a sand trap that was only about 200 yards out, and it bounced twice before going in it. Previously (and now), I carry that trap by 50+ yards. It was painful.
I saw three teaching pros, and one was finally able to help me. I think, in retrospect, that it probably had alot to do with tension, but this tip helped me alot.
The pro saw on video that I was coming a little bit forward (towards the ball, not towards the target), so he had me try to slightly press my left heel into the ground to initiate my downswing.
This 'seems' like it would actually cause you to go forward, but what it actually did to me was to get me to put my weight towards my heel, which helped prevent me from falling towards my toes. If you look at impact when most pros swing, their forward leg is pretty straight when they make contact with the ball.
I don't do that anymore, and I think my really light grip helps the club swing down rather than forward.
Not sure if this will help, but this was my experience with that problem.
