I couldn't complete the download of ROTJ either. I tried three times.
I assume, RickWJ324, that you decoded the incomplete blocks? It often helps. There's nothing else I can suggest.
Ewokgroomer's ROTJ looks rather good, and I believe the quality loss is small. I know it's not quite what you wanted, but frankly I don't believe the BD-50 size is necessary. I only tried to download it as there was no BD-25, and Adywan's AVCHD will be a while yet (WG's BD-25 of ROTS looks great though). I would encourage you to give Ewokgroomer's release a go. It's much smaller and won't take long to download, and if you're not happy, you can keep trying to find WG's, and you've lost nothing. :-)