i got an alert saying 'clean the charging contacts' but they look fine? it's not docking right.

Diagnosis

The "Clean Charging Contacts" error on the iRobot Roomba Combo j9+ is rarely caused by visible debris like hair or dust. Instead, the root cause is typically a microscopic layer of oxidation or a chemical film. This happens when floor cleaning residues (like ammonia or surfactants from wet mopping) or mineral deposits from hard water settle on the gold-plated contact points. Even if the metal looks shiny, this non-conductive layer creates high electrical resistance, preventing the robot from detecting the base or maintaining a steady charge. You can confirm this by attempting to manually push the robot onto the Clean Base. If the robot "beeps" as if it has docked but then immediately slides back or reports a charging error within 30 seconds, you are dealing with a connectivity issue rather than a mechanical alignment problem. In some cases, the spring-loaded pins on the Clean Base can become slightly recessed or "sticky," meaning they don't make full contact with the robot's charging plates even when the unit is physically seated.

How to Fix It

To restore a perfect electrical connection, you need to physically abrade the oxidation layer without scratching the gold plating. Follow these exact steps:

1. Power down the Roomba Combo j9+ completely by pressing and holding the Clean button until the ring light goes dark.
2. Flip the robot over and locate the two large gold-plated charging contact pads on the underside.
3. Take a high-quality white or pink pencil eraser. Rub the eraser firmly across the gold pads in a circular motion. You are looking to remove the invisible film; the pads should look slightly brighter after this process.
4. Use a can of compressed air or a dry microfiber cloth to wipe away any eraser crumbs. Ensure no debris remains in the crevices around the pads.
5. Move to the Clean Base. Locate the three metal charging pins. Use the same pencil eraser to clean the tips of these pins. If the pins are recessed, gently press them in and let them spring back to ensure they aren't stuck.
6. Wipe the charging pins with a cotton swab dipped in 70% Isopropyl Alcohol to remove any remaining oils. Let them air dry for 60 seconds.
7. Place the robot back on the dock manually and observe the light ring. It should transition to a solid white or amber charging indicator immediately.

If That Didn't Work

• Check for Base Displacement: Ensure the Clean Base is against a flat wall with at least 1.5 feet of clearance on either side. If the base has shifted even an inch, the j9+ may struggle to align the contacts perfectly, triggering the "Clean Contacts" alert as a false positive for a poor connection.
• Inspect for Pin Deformation: Look closely at the Clean Base pins. If one pin is pushed further back than the others, the robot cannot make a secure circuit. You can sometimes gently pull the pin forward with a pair of tweezers, but be careful not to snap the internal spring.
• Hard Reset the Logic Board: Perform a soft reset by pressing and holding the Clean button for 20 seconds. This clears the temporary error cache and forces the robot to re-poll the charging circuit.
• Test on a Different Circuit: If the base is plugged into a surge protector or extension cord, move it directly to a wall outlet. Voltage drops in cheap power strips can sometimes mimic a "dirty contact" error because the robot isn't receiving the full expected current.

Heads Up

• Never use steel wool, sandpaper, or abrasive scouring pads on the contacts; this will strip the gold plating and lead to permanent corrosion.
• Avoid using bleach-based cleaners near the Clean Base, as the fumes can accelerate the oxidation of the charging pins.
• If you use a "mop-first" cleaning routine, ensure the robot's underside is completely dry before it docks to prevent water spots from forming on the contacts.
• Perform a quick "eraser wipe" of the contacts once every three months to prevent the buildup of oxidation, especially in humid environments.