In general, there are very few things that can go wrong in your system, which makes maintenance great. However, if you are going away for months or years, we recommend that you carry:
Fan Replacement: Keeping a spare fan (and electrical wiring) ensures the ventilation system remains operational.
Spare Lids: In case you drop or misplace a lid for the liquids, order a few extra.
Composting Medium: While not a “part,” having an extra supply ensures you can maintain the proper composting mix.
Having these items ensures that you can deal with most maintenance or repair needs without a trip to town, keeping your system running smoothly in off-grid situations.