Something that might be worth trying is to get some low temperature bismuth casting alloy that melts at 70 degrees C. Just build a brick box and pour it in.
The fact that the pulleys are tied together does not matter for a very simple reason, they are all the same size. It is a circumference/rotation thing, as every loop of string moves the same distance for a given shaft rotation.
You could try something like the joint found at the following link, then again it probably won't work for you as it does not hinge vertically. http://www.hamm.eu/e...3k-knickgelenk/
Not only are you coming up with some great parts, but you are doing it as someone self taught. Impressive. And I say that as someone who uses it 8hrs a day on average. Good luck with your heath.