Dumbo and other drafts...
Michael Barrier, who unwittingly drove my desire for historical information on animation through the invaluable magazine Funnyworld when I first came in contact with it through my mentor Børge Ring in 1978 (where I also saw my first animation drafts) notes on his great site that "unfortunately, I haven't figured out to get to the earliest installments, but a full page of later posts of the draft comes up when you click on the label "Dumbo.""
If you look to the right column, there you find the "Archives" links.
In the case of Dumbo, the first posts are from April 2010, so pressing that link will show them.
John V. wrote a very helpful comment: "As I eventually discovered, if some of the posts "drop off", then go to the last post displayed (this can only be done, I think, by clicking on the "comments" link, then on the title of the post) and on the right hand side of the page there will be links to the previous few posts. Then you can just continue to follow the posts back by clicking on each individual post title."