I’m currently working on 1 handed windmill and I have some certain problems with it.
1st off, the only tutorial for it was the 5A may one and that was taken off or private.
2nd. My problem is that I can’t keep the counterweight in constant motion with one hand like Tyler in the tutorial. All I can do is pinch the string and have the yo-yo push the counterweight string and get a tangled mess.
A heavier counterweight might help it keep momentum.
Try experimenting with having the yoyo further or closer to your finger.
Make sure you are moving your hand in a circular motion.
Hope this helps ;D