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Make sure to remove the excess water from the tip, that the cotton is only moist and not full of water. Also, that the aluminum completely covers the body of the pencil and part of the cotton, otherwise it will not conduct the touch correctly. mine works perfectly. If you use a cotton swab as a tip, you must cover it with an extra layer of cotton, which is more fluffy and not so rigid, it is what I have noticed that works better. When I start to have failures it's because everything has flattened or is very compact, and I have to replace the tip. I hope these tips help you.

Thanks for the detailed explanation. I'll try this and test it on my phone again.