First off a Jinma is not the same as a Yanmar. A John Deere is the same as a Yanmar for the most part.
I have the same Jinma tractor you do.
Front axle has a dipstick on either the right or left side. Its a red painted bolt on top of the axle. It uses 80W90 gear oil.
Gear box has a dipstick by the gear shift levers. Its a red painted bolt also. Again 80W90 gear oil
Hydraulics should be checked with the FEL on the ground and 3 point down. Its behind the back seat. Most use AW32 hydraulic oil.
The engine has a dip stick on the left hand side. A good quality 15W40 Diesel Rated Motor Oil here.
The engine also has a seperate sump for the injector pump. There is a Mushroom cap for filling and whats called a site bolt on the side that takes a 10MM wrench to remove. Mine has a little drain on it. You fill it until oil comes out the site plug. This may take 30 minutes for the oil to settle. I use SAE 30 motor oil. Some use 15W40 just like in the engine and others use ISO100 Compressor Oil. No right or wrong answer here. Just as long as it has oil and is changed regularly. I do mine every other oil change or 100 hours.
By the way the proper way to check any dipstick that threads in is to unscrew it, wipe it clean, then insert without threading in and pull out and check.
Chris