I can. I can get it into any of the 4 gears in either high or low either when the engine is off or on. Is that good or bad?
If you can get it in and out of gear with the engine off the clutch is not releasing. It either may need adjusted or replaced. Have you smelled something similar to burning brakes? If the tractor is moving real slow the clutch may be slipping real bad. You may want to check the owners manual on the adjustment procedure.