2001 140h Will only go forward all reverse gears. We only spend if machine is off the ground forward gears seem to be OK just reverse gears.
Please post a Serial Number. There must be a dozen models of 140H out there. It would be nice to know exactly which one you have. Check the condition of the oil. Is it clear and bright or dark and cloudy.? Does it smell burned.? Next you need to inspect the transmission suction filter for the presence of burnt material. You will need to drain the oil to do this. Again with a Serial Number I can post up some instructions specific to your machine.
As I mentioned above check on the oil condition (smell, colout) first before moving on to the screens. Here is the procedure for the magnetic screens (there are two). If you find any material at all on them please take photos of it and post them up.