Upgraded firmware to latest, so 2.05. Using Prusa slic3r. Gcode, same issue with many models but copied are the start and end portions of one I tried:
; generated by PrusaSlicer 2.1.0+win64 on 2019-12-01 at 18:13:35 UTC
;
; external perimeters extrusion width = 0.60mm
; perimeters extrusion width = 0.60mm
; infill extrusion width = 0.68mm
; solid infill extrusion width = 0.68mm
; top infill extrusion width = 0.68mm
; support material extrusion width = 0.52mm
; first layer extrusion width = 0.63mm
M107
M190 S85 ; set bed temperature and wait for it to be reached
M104 S240 ; set temperature
G28 ; home all axes
G1 Z2 F8000 ; lift nozzle
G1 X150 Y10
M109 S240 ; set temperature and wait for it to be reached
G21 ; set units to millimeters
G90 ; use absolute coordinates
M82 ; use absolute distances for extrusion
G92 E0
; Filament-specific end gcode
;END gcode for filament
M104 S0; Set Hot-end to 0C (off)
;M140 S0; Set bed to 0C (off)
G91
G1 F1800 E-2
G1 F5000 E-3 Z5
G90
G28 X0 ; home X axis
M84 ; disable motors
; filament used [mm] = 3032.0
; filament used [cm3] = 7.3
; filament used [g] = 7.3
; filament cost = 0.1
; total filament used [g] = 7.3
; total filament cost = 0.1
; estimated printing time (normal mode) = 2h 10m 7s
; avoid_crossing_perimeters = 0
; bed_custom_model =
; bed_custom_texture =
; bed_shape = 0x0,280x0,280x300,0x300
; bed_temperature = 85
; before_layer_gcode =
; between_objects_gcode =
; bottom_fill_pattern = rectilinear
; bottom_solid_layers = 4
; bridge_acceleration = 0
; bridge_angle = 0
; bridge_fan_speed = 100
; bridge_flow_ratio = 0.9
; bridge_speed = 10
; brim_width = 5
; clip_multipart_objects = 0
; complete_objects = 0
; cooling = 1
; cooling_tube_length = 5
; cooling_tube_retraction = 91.5
; default_acceleration = 0
; default_filament_profile = ""
; default_print_profile =
; deretract_speed = 0
; disable_fan_first_layers = 2
; dont_support_bridges = 1
; duplicate_distance = 6
; elefant_foot_compensation = 0
; end_filament_gcode = "; Filament-specific end gcode \n;END gcode for filament\n"
; end_gcode = M104 S0; Set Hot-end to 0C (off)\n;M140 S0; Set bed to 0C (off)\n\nG91\nG1 F1800 E-2\nG1 F5000 E-3 Z5\nG90\n\nG28 X0 ; home X axis\nM84 ; disable motors\n
; ensure_vertical_shell_thickness = 0
; external_perimeter_extrusion_width = 0.6
; external_perimeter_speed = 30
; external_perimeters_first = 0
; extra_loading_move = -2
; extra_perimeters = 1
; extruder_clearance_height = 20
; extruder_clearance_radius = 20
; extruder_colour = ""
; extruder_offset = 0x0
; extrusion_axis = E
; extrusion_multiplier = 1
; extrusion_width = 0.6
; fan_always_on = 0
; fan_below_layer_time = 60
; filament_colour = #29B2B2
; filament_cooling_final_speed = 3.4
; filament_cooling_initial_speed = 2.2
; filament_cooling_moves = 4
; filament_cost = 11
; filament_density = 1
; filament_diameter = 1.75
; filament_load_time = 0
; filament_loading_speed = 28
; filament_loading_speed_start = 3
; filament_max_volumetric_speed = 0
; filament_minimal_purge_on_wipe_tower = 15
; filament_notes = ""
; filament_ramming_parameters = "120 100 6.6 6.8 7.2 7.6 7.9 8.2 8.7 9.4 9.9 10.0| 0.05 6.6 0.45 6.8 0.95 7.8 1.45 8.3 1.95 9.7 2.45 10 2.95 7.6 3.45 7.6 3.95 7.6 4.45 7.6 4.95 7.6"
; filament_settings_id = ApolloX
; filament_soluble = 0
; filament_toolchange_delay = 0
; filament_type = ABS
; filament_unload_time = 0
; filament_unloading_speed = 90
; filament_unloading_speed_start = 100
; fill_angle = 0
; fill_density = 15%
; fill_pattern = triangles
; first_layer_acceleration = 0
; first_layer_bed_temperature = 85
; first_layer_extrusion_width = 0.63
; first_layer_height = 0.22
; first_layer_speed = 10
; first_layer_temperature = 240
; gap_fill_speed = 30
; gcode_comments = 0
; gcode_flavor = reprap
; gcode_label_objects = 0
; high_current_on_filament_swap = 0
; host_type = duet
; infill_acceleration = 0
; infill_every_layers = 1
; infill_extruder = 1
; infill_extrusion_width = 0.68
; infill_first = 0
; infill_only_where_needed = 0
; infill_overlap = 0%
; infill_speed = 60
; interface_shells = 0
; layer_gcode =
; layer_height = 0.16
; machine_max_acceleration_e = 10000,5000
; machine_max_acceleration_extruding = 1500,1250
; machine_max_acceleration_retracting = 1500,1250
; machine_max_acceleration_x = 9000,1000
; machine_max_acceleration_y = 9000,1000
; machine_max_acceleration_z = 500,200
; machine_max_feedrate_e = 120,120
; machine_max_feedrate_x = 500,200
; machine_max_feedrate_y = 500,200
; machine_max_feedrate_z = 12,12
; machine_max_jerk_e = 2.5,2.5
; machine_max_jerk_x = 10,10
; machine_max_jerk_y = 10,10
; machine_max_jerk_z = 0.2,0.4
; machine_min_extruding_rate = 0,0
; machine_min_travel_rate = 0,0
; max_fan_speed = 30
; max_layer_height = 0
; max_print_height = 400
; max_print_speed = 80
; max_volumetric_speed = 0
; min_fan_speed = 15
; min_layer_height = 0.07
; min_print_speed = 5
; min_skirt_length = 0
; notes =
; nozzle_diameter = 0.6
; only_retract_when_crossing_perimeters = 0
; ooze_prevention = 0
; output_filename_format = [input_filename_base].gcode
; overhangs = 1
; parking_pos_retraction = 92
; perimeter_acceleration = 0
; perimeter_extruder = 1
; perimeter_extrusion_width = 0.6
; perimeter_speed = 60
; perimeters = 3
; post_process =
; print_host = 192.168.1.24
; print_settings_id = ABS
; printer_model =
; printer_notes =
; printer_settings_id = D9
; printer_technology = FFF
; printer_variant =
; printer_vendor =
; printhost_apikey =
; printhost_cafile =
; raft_layers = 0
; remaining_times = 0
; resolution = 0
; retract_before_travel = 2
; retract_before_wipe = 0%
; retract_layer_change = 1
; retract_length = 3.5
; retract_length_toolchange = 10
; retract_lift = 0
; retract_lift_above = 0
; retract_lift_below = 0
; retract_restart_extra = 0
; retract_restart_extra_toolchange = 0
; retract_speed = 100
; seam_position = aligned
; serial_port =
; serial_speed = 250000
; silent_mode = 1
; single_extruder_multi_material = 0
; single_extruder_multi_material_priming = 1
; skirt_distance = 2
; skirt_height = 1
; skirts = 2
; slice_closing_radius = 0.049
; slowdown_below_layer_time = 20
; small_perimeter_speed = 30
; solid_infill_below_area = 70
; solid_infill_every_layers = 0
; solid_infill_extruder = 1
; solid_infill_extrusion_width = 0.68
; solid_infill_speed = 50
; spiral_vase = 0
; standby_temperature_delta = -5
; start_filament_gcode = "; Filament gcode\n"
; start_gcode = G28 ; home all axes\n;G29 homing?\n\nG1 Z2 F8000 ; lift nozzle\nG1 X150 Y10\n
; support_material = 1
; support_material_angle = 0
; support_material_auto = 0
; support_material_buildplate_only = 0
; support_material_contact_distance = 0.2
; support_material_enforce_layers = 0
; support_material_extruder = 1
; support_material_extrusion_width = 0.52
; support_material_interface_contact_loops = 0
; support_material_interface_extruder = 1
; support_material_interface_layers = 1
; support_material_interface_spacing = 0
; support_material_interface_speed = 100%
; support_material_pattern = rectilinear
; support_material_spacing = 5
; support_material_speed = 60
; support_material_synchronize_layers = 0
; support_material_threshold = 0
; support_material_with_sheath = 1
; support_material_xy_spacing = 50%
; temperature = 240
; thin_walls = 1
; threads = 4
; toolchange_gcode =
; top_fill_pattern = rectilinear
; top_infill_extrusion_width = 0.68
; top_solid_infill_speed = 30
; top_solid_layers = 4
; travel_speed = 150
; use_firmware_retraction = 0
; use_relative_e_distances = 0
; use_volumetric_e = 0
; variable_layer_height = 1
; wipe = 1
; wipe_into_infill = 0
; wipe_into_objects = 0
; wipe_tower = 0
; wipe_tower_bridging = 10
; wipe_tower_rotation_angle = 0
; wipe_tower_width = 60
; wipe_tower_x = 180
; wipe_tower_y = 140
; wiping_volumes_extruders = 70,70
; wiping_volumes_matrix = 0
; xy_size_compensation = 0
; z_offset = 0
