I've been looking for a long time for one of these, and this popped up on the bay without much of a description, it was clearly being sold by someone who didn't know much about it, from the photos, it looked like a 7750 movement holder to me, so I took a gamble, and was pleasantly surprised when it arrived, in perfect working order, but above all, it sure is for the 7750 movement
DSC07931 by Micky Aldridge, on Flickr
DSC07934 by Micky Aldridge, on Flickr
Think I may put it through my ultrasonic bath to remove the staining as its clear its been sitting unused for some time. All the pushers, pivot holders, and screws are free, so will remove those prior to that and grease them.
Next movement holder I want to get it the dedicated 7753 holder, probably get that from Boley.