Before you start it, feel the engine and be sure it's cold. A dificult to start engine might have been started before you got there to make sure it runs.
Look for black smoke in the exhaust, especially when revving the engine. Check the oil to be sure it's black. If it's clear or brand new, that might be hiding something. Be sure to check it again before you leave after running it awhile. Check the water and hydraulic oil too.
Check all the gears in both directions. Don't listen to any excuse you might be given. If it's not right, it will get worse and that's expensive.
Hydraulic cylinders leak all the time and are not too dificult to fix. Run it in high RPM's and check for leacks around the seals. Run the loader through it's movements and see if it's tight. Most are.
Put the outriggers down and see if they will lift the tractor. If it doesn't, then you might have hydralic pump problems. If the seals are leaking bad, that could be it to.
Try to lift the tractor in the air with the front bucket and the outriggers down. This will also tell you how much hydraulic preasure you have from the pump. It should lift the tractor easy.
Now run the hoestick through it's range of movements. Increase the accelerator and leave it there. If you can't dig, be sure to more it quickly to show you the worm bushings. If they are worn, you will hear them banging around. The bucket will probably be the worse, but it's also the most commmon.
With the accelerator still running high, get off the tractor and take a look underneath. This is when you'll see the leaks. When it's warm, under high RPM's and after you've used the hydraulics. Some leaks are easy and simple to fix, others are not. Hoses are simple and easy. Cylinders are more work, but after you've done one, you can do the rest. Pumps and valves are very bad and will only get worse. Look to be sure you know where the leaks are coming from!!
Leave the outriggers down, and put the hoe stick in the air, straigt out. Lower the front loader bucket all the way to get the front tires off the ground. Turn off the tractor. Watch the front bucket, the hoe stick and the outriggers to see if they stay in position. If they move, you have problems.
Check the oil and fluids again. Look underneath again for puddles.
Check the paint. Is there new paint? Is it covering up something? Are there any new parts? Why are they there?
Look at the tires. Are there any tears, rips or chunks missing? Ths usualy means construstion work and lots of abuse.
If you are not comfortable with anything on it, walk away. Ther is always another deal out there, and the longer you wait, the more money you will save. If you buy a money pit, you won't be saving anything and could easily spend more on a used one than a new one.
Good luck,
Eddie