There were some wear spots on the trap parts and after 50 years it was time. I have replaced the aperture shoes and aperture shoe guides on the film traps. The pressure pads on the door/gate look in good shape and haven't been replaced. The focus problem was also there with the original parts which is what prompted the replacement in the first place.
I thought I had it solved after a few adjustments to the door/gate lateral position but when a splice went through it jumped out of focus again.

There are no adjustments available on the trap except the position of the lateral guide rollers. The aperture shoes and aperture shoe guides are aligned with pins.

Just for the hell of it I assembled one leaving out the side aperture shoe guides (Film Trap parts G-249 & G-250). Seems to work fine. Focus is good across the screen. However, I'm reluctant to permanently leave these parts out. I'm sure they were in there for some reason.

If not, swap the major gate parts and see if the problem follows.

Sounds like a mis-alignment of some sort, or uneven tension of the pressure pads. Take a look at the trap. Are some of the pressure pads clogged on one side so they don't seat properly or supply an even pressure to both edges of the film?

If the problem is in both machines, it could be the projection lens. What is the lens manufacturer, and what are the lens f-stops and focal lenghts?

Also, is your projection lamp properly focused and not creating a "hot spot"?

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Flat or scope? What's your picture size? How long of a throw do you have? (These are the most important question I have right now.) What is your lens size?

If this focus problem is with a Scope lens, it could be out of the range of astigmatism correction....

I find it a little odd that your problem exists in both machines. To me, that is unlikely, but I will admit it is possible.

Other that that, I have no other ideas at this time. Maybe some of the old-timers could be of more help.

Check your alignment as Gordon suggests. You might find something.

I presently have a film trap from an E-7 sitting in my lap right now, and I don't really see anything that could cause your problem, unless the lateral film guide roller is squished and frozen. That would cause excessive cupping of the film. Is the inboard flange free, and does it snap back when you push it laterally and let it go? If it does not budge when you try to push it laterally, it is crudded up.

It has been my experience that sometimes you have to punch the dowel pins in on one side (preferably outboard side) and manually adjust the guide. Apparently through the years, the hole for the guide dowels got misplaced due to drilling errors. The Ballentyne "75" gate gauge will not fit in mine, but it works well with Brenkerts, Simplex XL's, and naturally, the Ballentyne Pro-35.

What to use as a gauge to be accurate is a good question, but I have used a hunk of new polyester stock quite successfully.

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I think some of these movements have enough "slop" in the starwheel shaft sprocket bolt hole to adjust the lateral position of the sprocket by a .00* inches or so.

Since I never had a gate gauge to fit the E-7 trap, I never tried it. I just aligned them with the sprocket shoe when I replaced some of them. It seemed to work out OK. But I do know it has a little slop to play with.

I don't think his problem is with the sprocket alignment. I think it is the guides are just too close together. Your suggestion about what to do about the locating holes on the guides will probably cure his problem. Generally, I just drove those pins flush with the rails. Saves alot of hassle screwing around with a file.

And, I learned something about the gauge dimensions from you. I did not know about the offset. Thank you.

Paul

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