The battery is to be fully charged before starting to diagnose the problems with the starter. Should the starter fail to start when the switch is used, examine that in the case of an automatic transmission the shift lever remains in the Neutral or Park position, or in the case of a manual transmission the clutch pedal has been pressed. Ensure that the battery is recharged and that all the wires at the battery and starter solenoid terminals are clean and well attached. When the starter is turning but the engine is not cranking, then the overrunning clutch in the starter is slipping and needs to be replaced. When the starter is not working at all and the solenoid clicks the problem can be the battery, the major solenoid contacts, or the starter itself, or the engine can be seized. When the solenoid plunger cannot be heard when the switch is actuated, then the battery is possible to be flawed, the fusible link might have been burnt, or the solenoid could be faulty. To test the solenoid, place a jumper lead between the ignition switch wire terminal and the battery positive on the solenoid, in case the starter switches on, the solenoid is functioning and there is a problem with the ignition switch, neutral start switch or wiring. In case the starter is also not functioning, take out the starter/solenoid assembly to disassemble, test, and repair. When the starter has a slow crank, make sure that the battery is charged and that all the terminal connections are tight; a partially seized engine or a wrong oil viscosity may also result in slow cranking. Start the engine until it is up to normal operating temperature after which the coil wire is disconnected to the distributor cap and grounded on the engine. Attach a positive voltmeter lead to a positive battery post and a negative voltmeter lead to a negative battery post. Turn on the engine making voltmeter readings as soon as a constant figure has been shown taking not more than 15 seconds of starter action at any time. A reading of 9 volts or above and normal cranking speed is good but when the reading is 9 volts or above and the cranking speed is slow then the motor is defective. When the reading is lower than 9 volts and the cranking speed is slow, it might result in burning of the solenoid contacts, bad starter, discharging of the battery, or a faulty connection.