Ian, I have some of those really old tanks too.  I don't use them.  They were always a pain to load.  The Paterson and compatible reels are a dream by comparison.  I hear what you're saying about the clips.  I have them, but over the years, they've either stretched a bit or have worn, and no longer grip as tightly as they once did.  Some of my reels don't grip the center core tightly enough either, making twirling stick agitation ineffective.   The rubber bands solved both problems.  Wrap it tightly around the core and push it down over the topmost reel as far as she'll go.  It won't move after that.