Here is my home made feather tension tool with custom hardened spring.
i used the wire off of an old remote control car antenna as my steal (it was quite similar to music wire) prior to using this tool i felt like a novice now I'm opening all sorts of stuff. I highly recommend either making one of these or buying one. sorry for the grainy shot
PS, not trying to push products here but if any one has a custom tool request but is not comfortable in the shop i would love to build and sell it to you for a nominal fee. I love building tools in my metal shop and am always looking for new ideas.