Diagnosis
The paper pickup roller in the main tray is worn smooth or has paper dust/debris built up, causing it to slip and the gears to grind.
How to Fix It
Remove all paper from tray 1. Lift the tray fully open and look at the rubber pickup roller at the back-right corner. Clean it with a lint-free cloth dampened with warm water. Rotate it to clean the entire surface, then dry it thoroughly before reloading paper.
If That Didn't Work
The separation pad (a small felt pad behind the roller) might be glazed. You can lightly roughen its surface with a clean pencil eraser to restore friction. Replace the paper; ensure you're not overfilling past the stack guide.
Heads Up
This noise often gets worse with heavier cardstock or recycled paper. For best results, use standard 75-90 gsm paper and fan the stack before loading.