Hi
can anyone tell me if the spring across the top of the door is supposed to run the length of the bar only when I try to tension it it pulls towards the other side of the door as it compresses and won't stay in the original position

Shaun, September 2015

Thanks but I have searched endless sites and videos on this and no one mentions whether the spring actually compresses when tensioned. Before my cables snapped the spring ran almost the full length of the bar but as soon as I release the two screws and begin to tension it pulls to the right side of the door and is quite a distance from where it was.. oh and the link you supplied doesn't work

Shaun, September 2015

Think about it. The spring is to balance the rotating force of the shaft.

Why, oh why doesn't anyone search for themselves? 30 seconds! that's all it took to find a Really Useful Guide.

Scroll down about half way and you will learn how to tension a Henderson spring.

http://www.garagedoor-spares.com/technical-guides/

XX, September 2015