Prusa MK3S+ Maintenance

Regular maintenance checklist for the Original Prusa i3 MK3S+. If there is more than one MK3S+, go through the whole checklist for each printer. It follows Prusa's own guide: i3 Printer Regular Maintenance.
How often
Interval
What
Every couple hundred print hours
Cleaning, axes, belts, extruder, fans, sheets (sections 2 to 7)
Every 600 to 800 print hours, or at least yearly
Electronics check (section 8)
Supplies
Prusa Lubricant (Prusa Lubricant Applicator Set). Acceptable alternatives per Prusa: Super Lube synthetic grease, GLEIT-µ HF 400, Mogul LV 2-EP. Avoid very high viscosity grease.
Isopropyl alcohol (IPA) and paper towels
Compressed air, small brass brush, tweezers, cotton swabs
Allen keys, needle-nose pliers
Acetone (Smooth PEI sheet only)
Do not lubricate the Z-axis lead screws or trapezoid nuts. Prusa explicitly warns against this.
1. Before you start
Note the print hours from LCD > Statistics.
Unload filament.
Note the firmware version under LCD > Support (you will compare it in step 10).
2. General cleaning
Brush or vacuum filament bits, dust and broken supports from the frame and under the heatbed.
Heat the nozzle and brush off old plastic with a brass brush. Keep the brush off the thermistor and heater wires.
3. Smooth rods and bearings (X, Y, Z)
Roll each smooth rod between your fingers and feel for grooves or scratches. Note any damaged rods.
Wipe each rod clean with a dry paper towel.
Apply a thin film of Prusa Lubricant to each rod and run the axis end to end several times (Prusa maintenance tips guide).
If an axis still feels rough, remove the bearings, clean them with IPA, and grease the inside with a pea-sized amount (bearing maintenance article).
Check that the X-carriage-back screws and Y-bearing U-bolts are snug but not overtightened. Overtightening deforms the bearings and scratches the rods.
4. Belts and pulleys
Clear debris from the belt pulleys and idlers.
Confirm each pulley grub screw is tight against the flat of its motor shaft.
Pluck the X and Y belts: they should give a low bass note.
Check LCD > Support > Belt status. Target values are 260 to 290.
Adjust if out of range: Adjusting belt tension (MK4/S, MK3.9/S, MK3.5/S, MK3/S/+).
5. Extruder (Bondtech gears and idler)
Open the idler door (one screw on the MK3S+).
Cover the PTFE tube entry with a cotton swab, then clean both Bondtech gears with a brass brush, rotating a few degrees at a time through a full turn. Blow out the debris.
Verify the drive gear is aligned with the filament path and its grub screw is tight (Checking/re-aligning the Bondtech gear).
Confirm the idler shaft and bearing spin freely.
Optional: a tiny amount of non-oil grease on the outward-facing gear teeth only. Keep it off anything that touches filament.
Check idler screw tension: the head should be roughly flush with the extruder plastic (Idler screw tension).
6. Fans
Hold each propeller still and blow out dust with compressed air. Never spin a fan with air.
Remove plastic strings with tweezers.
Confirm the hotend fan and the print (part cooling) fan both spin freely by hand.
7. Print sheets
Clean each steel sheet with IPA; use dish soap and warm water for a deeper clean.
Acetone only on the Smooth PEI sheet, never on Textured or Satin (Flexible steel sheets guidepost).
Note any sheets with gouges or worn coating.
8. Electronics (every 600 to 800 hours, or at least yearly)
Power off and unplug the printer.
Inspect cables for pinching, rubbing or worn insulation, especially the heatbed cable bundle.
Blow dust out of the Einsy electronics enclosure.
Gently tug-test the PSU and heatbed power connectors, and retighten any terminal screws that move (Einsy RAMBo wiring reference).
9. Nozzle
Inspect the nozzle for wear (rounded tip, enlarged hole) or damage.
Replace it only if print quality stays poor after everything above (Changing or replacing the nozzle).
10. Firmware and slicer
Update to the latest stable MK3S+ firmware if it is behind (How to update firmware MK3S+).
Confirm the shop computers have a current PrusaSlicer.
11. Recalibrate
Prusa recommends recalibrating after maintenance.
Run Selftest from LCD > Calibration (fans, axes, heaters).
Run XYZ calibration if bearings, rods or the frame were disturbed (XYZ calibration MK3/MK3S). If the nozzle catches the paper, the SuperPINDA may need to be lowered slightly.
Run First layer calibration and set Live Z for each sheet in use (Basic calibration articles).
Print a small test part and inspect the first layer.
Afterwards
Record anything you found, what you did about it, and whether follow-up is needed. If the printer is not safe to use, tag it out of service: see Shop Safety: Tagging a Tool Out of Service and Reporting It.