I'm getting a problem where my Eumig S938 projectors will only focus half of the image with some Derann era polyester films. It's an intermittent problem and doesn't necessarily affect the same film twice. I believe it may be to do with warping in the gate. My Eumig ex-employee friends in Austria told me that Eumig projectors were never tested with polyester film, so it was always an unknown quantity, although the issue must be present in other manufacturers' projectors.

Do any of you experience the same issue and, if so, do you have solutions?

I havnt myself Martin, but it's interesting what you said regarding projectors not being tested with polyester. Bill Parsons and Kevin Brown mentioned this to me a few years ago. When i had a problem on one of my 16mm projectors where the gate noise was very loud, i was told then that all our projectors were made for, and adjusted for the common film stocks of the day. In the later years when the thin polyester films came about, adjusting the pressure plate/gates became a more difficult task. I know the projector runs very quite through the gate with polyester films, but when i had a problem with my SL2 after messing about with the gate myself, Kevin Brown sorted it and said, you can adjust it to run fine with older acetate stock, then run a polyester print and the film jumps, its a critical adjustment to make sure all the films run fine, even then, you may find the odd film may still want to jump, especially ones that have been over cleaned.
I guess with 8mm it becomes even more of a fine adjustment, and as parts wear, perhaps the thin stock films begin to either jump up and down, (as one of my 1200HD's did) or the focus becomes unstable. My 1200HD required a replacement backplate after some films became unsteady on screen, but it had done 40 odd years of projecting movies.
Hopefully one of our Eumig users will have an answer for you, otherwise, John White may be the best port of call. Let us know how you get on please.

Martin,

Why not contact John White about your problem, he used to work for Eumig and repairs all kinds of projectors, he may be able to help, if you haven't got his number just search John White Projectors and his site will be indicated with his contact details.

Here are details about John White
http://www.the8mmshedshop.co.uk/

Thanks, Barry and Maurice. John White has done several repairs for me over the years and doesn't live too far away either. I'll drop him a line, but I suspect he'll tell me the same as what my Austrian friends told me!

I suspect the gate is spring loaded Martin?, from the front facing backwards, or is it like the beaulieu facing forward, either way its just light spring pressure to keep it flat across the area. I'm not familiar with this model so sorry i' can't be more specific, but your faced with a coil spring or leaf spring to obtain this uniformly, considering the age of the old girls its not wrong to suppose the springs are sagging a bit, less springy, this could be an easy fix, if you have a service manual, sometimes they say what these should be, like the take up tensions on projectors, adjustment is needed, if john white worked for them, he would probably know what this would be, and the tolerance of what you can get away with, at least you haven't blown up the electronics, now that would be a headache.................