it's making a horrible grinding or screeching noise from the back right side every time it picks up paper.

Diagnosis

The grinding or screeching noise emanating from the rear right quadrant of the Canon imageClass LBP236dw is a classic symptom of a failing pickup roller assembly or a misalignment in the registration gear train. When the rubber on the pickup rollers becomes "glazed"—meaning it has worn down into a hard, smooth, shiny surface—it loses the coefficient of friction necessary to grab the paper. Instead of a clean pull, the roller slips against the stock, causing the drive gears to skip teeth or vibrate violently against the plastic chassis, creating that high-pitched screeching sound.

This is often exacerbated by "paper dust" or adhesive residue from label sheets building up in the gear housing, which increases resistance. To confirm this is the issue, perform a "manual feed" test using the bypass tray. If the noise persists but the paper feeds, the issue is likely a dry bearing in the registration roller. If the noise only happens during automatic tray feeding and results in a "Jam: Tray 1" error, the pickup roller assembly (Canon part RM2-8038-000) has reached its end-of-life and is slipping against the drive gear.

How to Fix It

To resolve this, you must replace the feed roller kit or deep-clean the existing assembly. Follow these precise steps:

1. Power down the LBP236dw completely and disconnect the AC power cable from the wall to prevent any electrical discharge from the fuser unit.
2. Open the rear cover by pulling the face-down output tray assembly outward. This exposes the internal paper path and the drive mechanism.
3. Locate the green release lever on the right-hand side of the chassis. Lift this lever upward and hold it in the open position to disengage the pickup assembly from the main drive gear.
4. Carefully slide the pickup roller assembly outward toward the rear of the machine. Be cautious not to force it, as there are small plastic guide tabs that can snap.
5. Remove the worn rubber rollers from the plastic hubs. If you are replacing the kit (RM2-8038-000), slide the new rollers onto the axles until you hear a distinct "click," ensuring they are seated flush against the hub.
6. Inspect the gear teeth for any white plastic shavings or debris. Use a can of compressed air to blow out the gear housing from the back right side toward the front.
7. Slide the assembly back into the chassis, ensuring the gear teeth align perfectly. Lower the green lever to lock the assembly into place.
8. Close the rear cover and reconnect the power. Run 10-15 blank pages to seat the new rubber rollers.

If That Didn't Work

• Clean the Separation Pad: If the noise is a "thumping" screech, the separation pad (the small rubber strip at the mouth of the tray) may be worn. Use a lint-free cloth dampened with 90% isopropyl alcohol to scrub the pad. If it is pitted or concave, it must be replaced to prevent the rollers from struggling to pull a single sheet.
• Lubricate the Drive Gears: If the grinding continues after roller replacement, the nylon gears may be dry. Apply a tiny amount of white lithium grease to the teeth of the drive gears using a toothpick. Do not use WD-40, as it degrades the plastic over time.
• Check for Foreign Objects: Use a bright flashlight to inspect the rear right cavity for small pieces of torn paper or staples. A single scrap of paper caught in the registration gear can cause a rhythmic screeching sound as the gear rotates.
• Inspect the Fuser Drive: If the noise happens *after* the paper has been picked up and is moving toward the output, the issue is actually the fuser drive gear. This requires a full fuser unit replacement, as the internal gears are not user-serviceable.

Heads Up

• Avoid using "rubber rejuvenator" sprays on the rollers; while they provide a temporary fix, they often attract more dust and lead to permanent roller slippage within a few hundred pages.
• Always use high-quality, 20lb bond paper. Using overly thick cardstock in Tray 1 puts excessive torque on the pickup gears, which accelerates the wear on the RM2-8038-000 assembly.
• When cleaning the interior, never touch the green drum of the toner cartridge with your bare fingers, as skin oils can cause spotting on your prints.
• Ensure the paper guides in the tray are snug but not tight; if the guides are too tight, the printer has to pull the paper with more force, causing the rollers to slip and screech.