| Symptom | Checks | Corrective action / notes |
|---|---|---|
| Bed will not heat | Heater wiring, thermistor reading, MOSFET, supply | |
| Hotend will not heat | Cartridge, thermistor, wiring, output | |
| Probe fails | Mounting, wiring, pin assignment, probe type | |
| Layer shift | Belt tension, pulley grub screws, binding, motor current | |
| Uneven first layer | Bed tram, gantry alignment, probe mesh, Z offset | |
| Extrusion inconsistent | Nozzle, filament path, extruder tension, temperature |
Record the exact error message, firmware version, recent changes, and test results before replacing parts.