Got a 48 harry Ferguson to20. It's hard stuck in 3rd gear. Shift fork wont budge. Pulled off gearbox cover to try and see if it's in two gears....cant tell. Had this happen before but I could manually move everything almost effortlessly and realigned everything and went back to tractoring. Now....cant move anything. Happened while driving. Was in 3rd, pressed clutch as I was needing to slow.....went to depress clutch and the engine bugged down and almost died. Repressed clutch, engine revved back up. Went to depress again and...bog down. No forward or backward movement at all, just bog down. Tried to tow it around to my garage to work on it.....wont budge!! Jacked up rear end, tires move opposite directions freely with clutch in or out. No gears in gear box turn at all. Nada!. Tractor is in a field, cant move it, and stuck in gear.