Resin maintenance centers on the vat, the FEP film at its base, and the LCD screen underneath. Before each print, inspect the FEP for cloudiness, pinholes, or a puddle-like sag. After each print, filter cured resin out of the vat rather than pouring it back into the bottle, and wipe drips off the build plate and gantry before they cure under ambient light.
Wipe spilled or leaked resin off the LCD screen and its protective film promptly with isopropyl alcohol on a lint-free cloth. Left to sit, resin can cure onto the anti-scratch film or work into gaps around the screen bezel. Check the area around the light source for dust too. The Mono 4’s LighTurbo array sits behind the screen, and an obstruction there shows up as an uneven or dim print rather than a clean, even cure.
Clean the build plate with IPA after every print and check that it seats flat and level. Follow Anycubic’s official leveling guide for the Mono 4 rather than a generic resin-printer routine, since z-offset and plate mounting differ between models.
If you run a separate wash-and-cure station, empty and filter its IPA or wash tank regularly, change fluid once it turns cloudy or resin-saturated, and keep the cure chamber free of dust and cured resin flakes. Replace the printer’s activated-carbon filter when odor control noticeably drops. It is a consumable part, not a permanent one.
Keep a simple log of vat cleanings, FEP condition, and screen wipe-downs. A sudden change, such as prints failing across the whole plate instead of one region, points to the FEP or screen rather than a slicer setting. Inspect the hardware before you start changing exposure times to chase what might be a physical fault.
When the FEP itself is due for replacement rather than just cleaning, the FEP film replacement guide covers the full procedure. The resin fill and change guide is a useful companion, since vat cleaning and resin swaps tend to happen around the same maintenance visits.