#define SDSS            10

//#define TRY_AUTOREPAIR_LCD_ERRORS

#define HEATED_BED_MAX_TEMP 130

#define FEATURE_CONTROLLER 2

#define ENDSTOP_PULLUP_X_MIN true

#define XAXIS_STEPS_PER_MM 800

#define X_ENABLE_ON 0

#define EXTRUDE_MAXLENGTH 100

  #define SIG_USARTx_RECV   SIG_USART1_RECV

  #define SIG_USARTx_RECV   SIG_USART1_RECV

Hello,  My units setting was #define EXT0_WAIT_RETRACT_UNITS 500.  I have set it to zero and will see what happens.

#define EXT0_WAIT_RETRACT_TEMP 150

Not sure if you can handle the high travel acceleration, but could work.#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND_Z 500

#define MAX_HALFSTEP_INTERVAL 1999#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND_X 500#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND_Y 500#define MAX_ACCELERATION_UNITS_PER_SQ_SECOND_Z 500#define MAX_TRAV

#define STEPPER_HIGH_DELAY 10

#define STEPPER_HIGH_DELAY 0

#define HAVE_HEATED_BED 0

#define EXT1_EXTRUDER_COOLER_PIN ORIG_FAN_PIN

#define X_ENABLE_ON 0

#define ENDSTOP_X_BACK_ON_HOME 1