What are the reasons for the starter not rotating?

[DelKing]

The reasons for the starter not rotating: 1. Insufficient battery charge or disconnected, loose, or poor contact of the connecting wires; 2. Burned main contacts of the starter electromagnetic switch, open circuit of the pull-in coil or hold-in coil; 3. Open circuit in the starter armature winding; 4. Bent or deformed starter armature shaft, excessive tightness in the assembly of the armature shaft and copper sleeve, friction between the armature core and magnetic poles, causing the starter not to rotate; 5. Severe burning of the commutator, excessive wear of the brushes, brushes stuck in the brush holder, or aging and loss of spring tension in the brush spring. Starters are classified by working principle into DC starters, gasoline starters, and compressed air starters.