The pre-operation checking of the forklift is essential part before commencing work. It should be conducted prior to a shift. Check the condition of the four tires, make sure the fork arms aren't damage and showing cracks and metal fatigue. You need visually inspect the machine's mast assembly, chains and other parts of the lift system. Under the bonnet, you need to check the condition of the battery and look for oil leaks, electrical wire burn, check the coolant are some of the issues need to be examined.
A forklift truck that is damaged or need repair or unsafe to operate should be reported for maintenance. The determination of fault is vital to see whether the machine can do its heavy tasks. OSHA requuires operators to conduct examination. You need to make sure you are wearing PPE's while performing this task. Usually company supervisor provide checklist to do such inspectioin.
Here's the video of a supervisor doing the necessary inspection of the forklift.