Solution:

Measure in millimeters how far the fainter area extends from the trailing edge.

Configure the following settings in [Advanced Settings] for the custom paper in use.

In [Paper Transfer Current; Trail Edge Dist], enter the value you measured in Step 1 plus an additional 10 mm.

In [Advanced Settings] for the custom paper in use, make a note of the present value in [Paper Transfer Current; Trail Edge].

Increase the scaling factor in the above setting by 10 percentage points.

Print the image. Is the problem resolved?

Repeat Step 5. If the problem persists even though you have increased the scaling factor by 50 percentage points, restore the value noted in Step 3 and go to the next step.

Decrease the scaling factor in the above setting by 10 percentage points.

Print the image. Is the problem resolved?

Repeat Step 8. If the problem persists even though you have decreased the scaling factor by 50 percentage points, restore the value noted in Step 3 and contact your service representative.