Most "broken" 3D printers aren't broken — they're under-maintained. Twenty minutes of routine care per month prevents 80% of failures. This is the schedule used in production print farms: weekly, monthly, and quarterly checklists that catch problems before they ruin a print or kill a part.
Weekly: wash the build plate, vacuum out fan debris, listen for new noises. Monthly: wipe rails, re-lube leadscrews, check belt tension, update firmware. Quarterly: deep-clean extruder gears, replace PTFE liner if present, audit cable strain reliefs, check screw torques, replace nozzle if heavy use.