864 with hand controls, start engine lower seat bar and press to operate, all lights light up as they should. however when i operate machine for about 30 seconds lift and tilt functions quit working and alarm chirps, with the lift and tilt light flashing. seems as if bics is locking out lift and tilt functions. shut off engine and it does the same thing, operates for about 30 seconds and locks out again. machine is dispaying no codes in the display, and it will still travel when this happens. any help on this issue would be greatly appreciated. thank you...