I have a 1969 Case 580 CK. I cant get the engine to budge. tried a lot of things. Is there maybe a problem in the drive train, clutch that won't allow engine to spin??? I have put trans.in neutral and pulled the tractor. OK. I then put trans. in high gear, 4Th. Then pulled it with another tractor. Engine wont budge...????? Thanks Guy.
It could have a spun bearing on the crankshaft or perhaps the hydraulic pump is locked up for some reason? I would start by removing the grill, radiator and hydraulic pump from front of tractor and see if the engine turns manually. To check for a damaged bearing you will need to remove the oil pan which will probably involve removing a large bracket on the front axle and maybe tie rod. I don't have a 580 but I do have early 70's 480B that I, unfortunately, recently went through this with. Take any of my advice with a grain of salt, I'm not a mechanic. Hopefully someone more experienced will chime in.
To answer your question, you mention a clutch. Does it feel normal? If you disengage it, can you then pull the tractor in gear? A little history of what happened prior to it locking up and some of the other things you mention having tried would help. Could be hydro locked with fuel or coolant. Can you turn the engine backwards any?