Glad to hear that you have solved your problem. Now that everything is aligned properly, you should have no great falloff problems printing full-frame.

Let me say, however, that although you now "can" crop by moving the easel about within the projected image, that Bob's method of centering the area to be printed in the lens' field-of-view is really the best practice. You can do this to an extent with your negative carrier by moving the negative in the carrier to center the area you wish to print as much as possible. "Up-and-Down" centering may not be possible due to the guides in the holder, but side-to-side certainly is and well worth doing. In the case of the print you are making, it certainly seems possible to me.

The reason for this is simple: lenses are sharpest and have the most even illumination in the very center. I try to get the portions of the negatives I print as close to the center as possible, although, admittedly, I don't go quite to the lengths Bob Carney does. And, although I trim-crop most of my images, I'm not really enlarging small areas of my negatives.

Summary: if you can better center the area of the negative you wish to print, it will be better to do so quality-wise.

Best and happy printing.