A forklift should be checked properly and given a test run before buying it. This applies specifically to trucks being acquired online. It is very important to detect potential issues with trucks purchased from companies on the Internet.
Starting the engine from cold is a good idea. Note whether there is excessive smoke and the ease with which the engine turns over. This is particularly crucial with trucks that have IC engines.
Testing the performance of the truck in challenging situations should be included in the test run. A skilled operator could operate the truck in reverse and forward, up the ramp.
You could perform your own inspection of an IC engine truck. On a clear part of floor, run the truck around for several minutes while a trained operator tests the hydraulic functions. After that, examine the ground underneath for signs of fluid leakage. Even seemingly insignificant leaking can lead to serious issues that will be pricey to repair later on.
The chains and masts must be checked by a qualified person. Check with and without a load that the mast operates smoothly. Watch for sticking or 'binding' of the mast. A warning sign is play in the mast channels or between the fork carriage and mast. One more is creeping down or creeping forward of the mast when loaded. These could be signs of issues with seals, ram or valve.
The mast might have been changed at some time if the truck is not new. Make sure that the mast and any fitted attachments follow the rating plate on a truck. Make certain that the sideshift is not sticking when loaded.
When checking the forks, look closely at the heel thickness for wear or damage. The manufacturer of the truck specifies minimum thickness. A loose fit might mean the carriage or hanger points are worn. Watch for cracks on the arms at mountings and heels.