If you have a Brother HL-2130 that suddenly stopped picking up paper, but still works with manual feed; this might be the problem. (Right side of body – side panel unclips, a few screws hold two metal plates on. Best disassembled resting on its left side so the cogs don’t run away.)
This part under the screwdriver is a little fragile – I think it might get whacked by the tray when you put it in. The small plastic clip that keeps it locked in place in that circular cutout can snap off, which then allows it to jam against the upper rollers rather than sliding the above cog over to meet the roller that finishes dragging sheets of paper through.
You might be able to work around this by using a soldering iron to melt the black plastic down crudely to keep the white assembly from travelling away from the base.
Good luck 🙂