Toyvo
I'm going to go out on the old limb and say the weight is cast iron, and the shaft certainly wouldn't be, so the weight is drilled to accept the shaft.
Replacement shafts and springs are available, while the weights are not..this would lead one to the conclusion that the weight is mechanically attached to the shaft.
If this is true, with the proper machinery and skills, you might be able to get the broken piece of shaft out of the weight and be home free.
Stuart
