When, exactly, did we become not permitted to repair our own equipment for this to change anything? I own some John Deere farm equipment and repair it myself, w

When, exactly, did we become not permitted to repair our own equipment for this to change anything? I own some John Deere farm equipment and repair it myself, when I don't hire my mechanic neighbour to do it for me, all the time. The parts desk down at the Deere dealership never had any qualms giving me the parts I needed.