The method I used works with anything flat and "solid." You can use screwdrivers, but they slip easily and are quite difficult to use for that reason. The paint sticks, if you have them, have lots of surface area which makes it relatively easy to push the latch open.
Here's a pic from someone else who had the foresight (not me) to make it a bit easier on everyone.
Insert one towards paint stick towards the rear (the first stick is a spacer, nothing more. It just opens the gap.)
Insert the second stick through the helmet lock crease from the right side (riding position.) This will be the stick that you use to push the lever in the picture above.
Remove the seat, take a slim flashlight and stick it in for light. You will be able to look in from the side that you are working (it's gonna be a slim area, so you're not going to see much) but you can work the stick and push towards the oppostie side and release the cable.
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Good luck and let us know how it goes.
