Friend just picked up a nice overall John Deere 400. Hydraulic steering and deck lift. When turning to the left from center, the mower deck and 3 point lever moves and the deck and 3 point lowers while turning. Can't find any physical interference so thinking it may a fault be in the hydraulic...
Here are my guys in the first picture, back to front, 1998 JD855, 1981 JD400, 1987 Craftsman GT/18 (this was my first tractor), 1991 Craftsman LT4000.
Joel