I’m not sure if your 706 has a torque amplifier, but my International 966 does. Without the engine turning the MCV hydraulic pump in the transmission, it has no brakes, no clutch engagement and barely any steering. So trying to pull to turn engine would not work. I would pull the injectors and the valve covers. You can put some lube down the cylinders that way and if one just has water in it, the water has somewhere to go. Pulling valve covers lets you see which cylinders had open valves. Water probably cqme in through an exhaust valve. I would then try the starter again. If that doesn’t work, I would see if I could get a socket and breaker bar on the front of the crankshaft, or pull the starter and try using a prybar on the flywheel through there. Diesel engines tend not to stick easy, so if the starter can’t spin it over with the injectors out, i would be prepared for the possibility of removing the head. I’m not a professional tractor mechanic, my diesel experience comes from working on Peterbilt trucks mostly. Another option for isolating which cylinder is stuck, would be to pull the oil pan. You would mark and remove your rod caps. Then with a soft punch, brass or hardwood tap each piston rod up. Try not to tear the tractor down more than you are willing to reassemble. Once you get engine freed thoroughly bleed all your injector lines, they will be contaminated with some dust after being off. Check your engine oil for water. If it shows overfull, that usually is not a good sign.