After searching high and low and trying to fix the film counter myself, to no avail due to the parts in question being unavailable I - gulp - came up with a fix: making a new red window for getting 12 (not 11) 6x6 exposures the lower-tech way.
I have linked my project below: http://www.shutterfly.com/lightbox/view.sfly?fid=0beb71695ee204c5d33ce936de451066