Well,
Since you can't find the actual replacement, here's a thought. Are you looking for the round part of the handle that's actually clear? If so, then, this is only a suggestion here, go to a plastics supply place and look for either Plexiglas or Polycarbonate tube, in the same outside diameter. Have them cut a section and then make it work for your handle. I'm not familiar with your setup and how it looks but, on ours, I'd try that remedy if I couldn't find a replacement. Ours says "Itasca" on it, in vertical letters so, I'd either loose those or, I'd pay to have them machined into the new tube.
Scott