Yeah, hollow.. Knowing this I assumed there must be some kind of compression mechanism holding the end weight in, so I loosened the screw and the weight started to move around, so I loosened it some more, pulled it out and did the other side.. At the time (many years ago now) I didn't consider myself some kind of mechanical genius but I've since come to discover that I must be. I never once thought 'ahh, these must be held in by some really complex nut retaining system fixed to the inside of a hollow tube'..
It still baffles me now, but every so often someone does it again.. Why, I just don't know..
Sounds overly flippant, it isn't meant to..