E-26 seems to be about impossible to do yourself but there are still labs that handle it. About $30/roll on up a few years ago.
Ron Andrews, who should know IF his claims are true (see below), says that IF you can get the rem jet backing off cleanly, which he has doubts about, then you can self process using the E-6 process, but colours will be wrong.
There is a lot on the web re Ektachrome processing BUT this comment from a man who claims that he helped design it and who then manufactured it is not encouraging. (There seems no good reason to not believe his claims BUT on the net, who knows?) From here Whole thread is worth reading in your case.
Ron Andrews , Mar 10, 2009; 01:42 p.m.
You hit one of my favorite topics. I helped design Process EM-26. I later had responsibility for manufactruing the film. The first few years of my kids lives were well documented with this product.
Unfortunately, Process EM-26 is no longer available. If you could get the rem jet backing off cleanly (a very big if) then you could process it in E-6. The color balance would be off, but film this old will have problems with contrast and color anyway.
Rocky Mountain Film Labs is willing to develop the film in their custom process for $48.50 with no guarantee of any image. If you have movies of bigfoot or Elvis (post 1974) it might be worth it.
Another poster on the same page says:
- Martin Baumgarten , Mar 10, 2009; 09:46 p.m.
Hi, this film is processed by my laboratory for $28 each [EM-26 type films 50ft] plus return shipping costs to wherever.
*There are only three labs left in the world that I'm aware of, that are still offering processing for old Super 8mm discontinued movie films:
* myself at Plattsburgh Photographic Services,
Rocky Mountain Film Lab in Colorado at http://www.rockymountainfilm.com/, and
Film Rescue in Saskatchawan, Canada at http://filmrescue.com/.
A few more claimed dpricessing sources are listed here dated 2006 and 2007.
This may be Rocky Mountains current E26 page
EM26 mention - not encouraging