Here are some different springs that fit on the needle to work for Darning. I'm pretty sure the second one would be the same as the third -but the top part is broken off. I know I have instructions for how to use them too. But with all of these, the needle tip sticks out below the spring, so it will contact the fabric first. Not having the correct fabric tension while sewing can cause all sorts of problems with the thread tension. If you sew with a hoop you don't really need a foot at all. You still need to make sure the tensioners are engaged though!
I've not tried any of these yet to see how they work -but this was what was sold as the "darning option" for the top clamp machines.
This is the only hopping foot I have for top clamp - made for Standard and that mfg has a much higher shank than the other top clamp feet, so I doubt it would work on the others even if you could get the needle hole to line up. This one is described as working for darning and machine embroidery. With this one, the foot will contact the fabric before the needle.
I don't like the type that hook to the needle bar and actually lift the presser foot up, bar and all. I'm too worried that over time it may cause the needle bar to slip down and get it out of time. But I have no idea if that would be a real problem or not.