Hi Roger. Eumig introduced the single sprocket models mainly as a money saving exercise as they were by that time already heavily in debt with the Austrian bank. That said the idea was to make the projected image steadier and to some extent it does improve and give a solid frame line on screen, at least with a decent film being used. I have a Stereo 926 which has the very same mechanism your machine has and it projects faultlessly. You’ll hear of people adding rollers to the machine for rewind guides and more but it is completely unnecessary and speaking for my machine it is very kind to film. The ‘coaxial reel’ models are always available cheaply as most like a more traditional machine, but the 905, 910, 912 and 926 can fairly easily be converted to a 2-blade shutter which increases light output no end, and adding the better Eumig f/1.2 lens is also a great idea. I often use mine which has the above upgrades for scope shows and it performs extremely well.
![[set5_b/set5_b/troll.gif]](./images/smilies/set5_b/set5_b/troll.gif "troll")
You can see my 926 here showing a vintage acetate film here. http://youtu.be/dJ7JpwrRM-w For the clip I feed the line audio out signal from the projector so not to hear the projector running by the way.