Windmill - Unequal pressure between the right and left

Is it the delivery side of the platen that has less pressure?

Happens on my older one. I just put a piece of thin hard packing material (tape, tissue, coated paper) on the side that needs more impression behind the base. Then adjust your rollers.

is the bearer bar on the left touching the bearer bar on the chase?
there should be a packer under the bearer on the clam.

The explanation is in the AGE of these presses; they are worn out.

The original make-ready instructions really do not apply any more. The make ready and shimming has to be done as the press and the job requires it. There are no rules for it, you have to develop a feel for it.

The impression is going to be different even when you freshly fill the main bearings with oil. You will also feel the difference how much pressure you have to apply to the oiling gun to squeeze the oil in. Usually oiling the delivery side bearing is with less pressure than the other side. Meaning that that bearing is more worn out than the other. The clam rocks from left to right under load, depending how big is the image and where is it’s centre.
It is like trying to push a furniture with your shoulder, your chest will rotate and your other shoulder will move forward.