Not climbing your driveway is not related to how the forklift truck was ordered.There are a few reasons why yours won't climb the driveway. Obviously first check the Trans fluid level, even if it is 2 quarts low that would create a problem.
If it's full then put the forks against a concrete wall, put it in forward and accelerate the engine to full RPM's. The tires should spin. If while doing this test the engine bogs down then either the timing is not set right or the fuel system needs adjusting. If the tires don't spin and the engine doesn't lose power, the issue is either that the inching valve isn't set correctly or the transmission is worn.
BTW- The brakes are self adjusting.