Good morning. There are many important parts of a wheel loader to inspect. The first thing is to check the loader for exhaust color and power. Secondly, look for frame cracks. Next check the center pin for wear. That repair is expensive. I would then check pin and bushings for wear.
Next check the hydraulic pumps for leaks and power. The last major component to check are the final drives. Look for leaks and listen for noise. Finally check the cab environment and controls.