It is my understanding that they made two types. The one shown in the picture there was for the Helix version (if I am not mistaken). The other models (Conion / Clairtone) only had 1 hole drilled in the front housing for a spring on the right lower post (as facing the box head on). I believe Caution has a picture floating around on here of what the other style factory spring looks like.
I made my own and it worked quite well. It's a watered down version of the spring in the picture above. It's been months since I made the spring and it's working like brand new.
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If you have a Tractor Supply they sell these spring kits which is what I purchased. There are many sizes and strength springs in there. It takes a fairly stiff spring to work properly.
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