Printer HL-L8350CDW Presses Groves in the Paper

Recently my HL-L8350 CDW lazer printer bagan pressing two vertical grooves in the paper. The printing and paper feed is normal otherwise (no paper jams). This happens after the printing,—the printing, especially photos, is damaged in the grooves. I looked at the rollers under the cartridges and as far into the paper path as I could without undoing fasteners, no deposits or obvious problems.