Found Some of the Episodes
From The Lost Media Wiki
I actually located a few of the episodes that are labeled as 'lost'. Did some searching for only a few minutes and found a dailymotion playlist with a bunch, although their image quality looks fairly low and the images themselves are reveresed. Based on the endings they look like DVD rips - they include a link to the Jim Henson site 'www.henson.com'. Some of the episodes included that are labeled as lost currently are 'Wembley's Egg', 'The Minstrels', 'Marooned' and 'New Trash Heap in Town'. Some don't have title cards that state the episode so I personally cannot verify if all of them are the real deal but it seems that way.
Link to the dailymotion playlist: https://www.dailymotion.com/video/x6rrifj?playlist=x5y8sa