diff --git a/CHANGELOG.md b/CHANGELOG.md
index 330bb833..e7e9b48d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -16,6 +16,8 @@ CHANGELOG for FlatCAM Evo beta
 - fixed some bugs in the Punch Gerber plugin
 - fixed some bugs where the 'pool' parameter was not passed when creating shapes collections (in 3D graphic mode); I wonder how it worked until now
 - added a new feature in the Isolation Plugin: now for all the isolation Geometry objects this plugin can do a supplementary simplification of the geometry using the tolerance parameter defined in the General Parameters. This should lead to a reduced number of tool lifts when doing corners
+- fixed aperture marking in Extract Plugin
+- in Extract Plugin if no Gerber object is selected then the first Gerber object in the project list is selected (if any)
 
 30.03.2022
 
diff --git a/appObjects/GerberObject.py b/appObjects/GerberObject.py
index 543e994a..cac0eaeb 100644
--- a/appObjects/GerberObject.py
+++ b/appObjects/GerberObject.py
@@ -1038,19 +1038,20 @@ class GerberObject(FlatCAMObj, Gerber):
         def job_thread(app_obj):
             with self.app.proc_container.new('%s ...' % _("Plotting")):
                 try:
-                    if aperture_to_plot_mark in self.tools:
+                    if aperture_to_plot_mark in app_obj.tools:
                         for elem in app_obj.tools[aperture_to_plot_mark]['geometry']:
                             if 'solid' in elem:
                                 if only_flashes and not isinstance(elem['follow'], Point):
                                     continue
                                 geo = elem['solid']
+                                s_geo = geo.geoms if isinstance(geo, (MultiLineString, MultiPolygon)) else geo
                                 try:
-                                    for el in geo:
+                                    for el in s_geo:
                                         shape_key = app_obj.add_mark_shape(shape=el, color=color, face_color=color,
                                                                            visible=visibility)
                                         app_obj.mark_shapes_storage[aperture_to_plot_mark].append(shape_key)
                                 except TypeError:
-                                    shape_key = app_obj.add_mark_shape(shape=geo, color=color, face_color=color,
+                                    shape_key = app_obj.add_mark_shape(shape=s_geo, color=color, face_color=color,
                                                                        visible=visibility)
                                     app_obj.mark_shapes_storage[aperture_to_plot_mark].append(shape_key)
                     app_obj.mark_shapes.redraw()
diff --git a/appPlugins/ToolExtract.py b/appPlugins/ToolExtract.py
index f0d8ba45..173b550f 100644
--- a/appPlugins/ToolExtract.py
+++ b/appPlugins/ToolExtract.py
@@ -124,7 +124,8 @@ class ToolExtract(AppTool):
         self.set_tool_ui()
         self.build_tool_ui()
 
-        self.app.ui.notebook.setTabText(2, _("Extract"))
+        # trigger this once at plugin launch
+        self.on_object_combo_changed()
 
     def connect_signals_at_init(self):
         # ## Signals
@@ -207,9 +208,18 @@ class ToolExtract(AppTool):
 
         # SELECT THE CURRENT OBJECT
         obj = self.app.collection.get_active()
-        if obj and obj.kind == 'gerber':
-            obj_name = obj.obj_options['name']
-            self.ui.gerber_object_combo.set_value(obj_name)
+        if obj:
+            if obj.kind == 'gerber':
+                obj_name = obj.obj_options['name']
+                self.ui.gerber_object_combo.set_value(obj_name)
+        else:
+            # take first available Gerber file, if any
+            available_gerber_list = [o for o in self.app.collection.get_list() if o.kind == 'gerber']
+            if available_gerber_list:
+                obj_name = available_gerber_list[0].obj_options['name']
+                self.ui.gerber_object_combo.set_value(obj_name)
+
+        self.app.ui.notebook.setTabText(2, _("Extract"))
 
     def build_tool_ui(self):
         self.ui_disconnect()
@@ -330,6 +340,17 @@ class ToolExtract(AppTool):
         # self.ui.apertures_table.setMinimumHeight(self.ui.apertures_table.getHeight())
         # self.ui.apertures_table.setMaximumHeight(self.ui.apertures_table.getHeight())
 
+        # make sure you clear the Gerber aperture markings when the table is rebuilt
+        # get the Gerber file who is the source of the punched Gerber
+        selection_index = self.ui.gerber_object_combo.currentIndex()
+        model_index = self.app.collection.index(selection_index, 0, self.ui.gerber_object_combo.rootModelIndex())
+        try:
+            grb_obj = model_index.internalPointer().obj
+        except Exception:
+            self.ui_connect()
+            return
+        grb_obj.clear_plot_apertures()
+
         self.ui_connect()
 
     def ui_connect(self):