diff --git a/modules/LoadLocalModel.py b/modules/LoadLocalModel.py
index d942b7f..be20e6a 100644
--- a/modules/LoadLocalModel.py
+++ b/modules/LoadLocalModel.py
@@ -84,6 +84,7 @@ def execute(self, context: Context) -> Set[str]:
         # so that an existing importer Operator can be wrapped at run-time
         # with a wrapper function that supplied other import arguments
 
+        logger.info(f"LoadLocalModel.execute self.mimetype: {self.mimetype}")
         try:
             handler, handler_name = handler_for_mimetype(self.mimetype)
         except KeyError:
@@ -153,7 +154,7 @@ class ImportGLTF2; function set_debug_log
 
 def handler_for_mimetype( mimetype:str) -> Tuple[Callable[..., Set[str]] , str] :
     """
-    return 2-tuple (func, label)
+    return 2-tuple (func, label), or raises KeyError
     function is the callable, may be Blender defined operator call such as 
     bpy.ops.import_scene.gltf 
     label a string used only for logging messages
@@ -166,8 +167,7 @@ def handler_for_mimetype( mimetype:str) -> Tuple[Callable[..., Set[str]] , str]
         
     mimetype_importer_dict = {
         "model/gltf-binary" :           GLTF_IMPORTER,
-        "model/gltf+json"   :           GLTF_IMPORTER,
-        "application/octet-stream"  :   GLTF_IMPORTER   
+        "model/gltf+json"   :           GLTF_IMPORTER  
     }
     
     return mimetype_importer_dict[mimetype]
diff --git a/modules/LoadNetworkModel.py b/modules/LoadNetworkModel.py
index 49e809b..452f0e5 100644
--- a/modules/LoadNetworkModel.py
+++ b/modules/LoadNetworkModel.py
@@ -9,6 +9,9 @@
 from bpy.props import StringProperty
 from bpy.types import Context, Operator
 
+from .LoadLocalModel import handler_for_mimetype
+from .editing.models import  mimetype_from_extension
+
 import logging
 logger = logging.getLogger("iiif.import_network_model")
 
@@ -84,8 +87,26 @@ def execute(self, context: Context) -> Set[str]:
                 # URL data downloaded to local_filepath and 
                 # http_mimetype set to the Content-Type (or to "")
     
+            # logic for figuring out a mimetype to decode the resource as a 3D asset
+            def choose_mimetype():
+                for mime_choice in (http_mimetype, self.mimetype):
+                    try:
+                        handler_for_mimetype( mime_choice)
+                    except KeyError:
+                        continue
+                    return mime_choice
+                
+                # if neither http_mimetype, self.mimetype are supported,
+                # try to get somethinf from the extension on the model_basename
+                try:
+                    return mimetype_from_extension( model_basename )
+                except Exception:
+                    pass
                     
-            mimetype = self.mimetype or http_mimetype
+                # if all else fails, return mimetype for glb as the default:
+                return "model/gltf-binary"
+                         
+            mimetype = choose_mimetype()
             
             # call the ImportLocalModel Operator to import the contents
             # of the local_filepath file into Blender as a Blender Object
diff --git a/modules/editing/models.py b/modules/editing/models.py
index 0439099..e2aa76a 100644
--- a/modules/editing/models.py
+++ b/modules/editing/models.py
@@ -63,6 +63,7 @@ def configure_model(    new_model : Object,
         if "format" in resource_data and resource_data["format"] != mimetype:
             message=f'resource format ${resource_data["format"]} does not match ${mimetype}'
             logger.warn(message)
+        resource_data["format"] = mimetype
     new_model["iiif_type"] = "Model"
     new_model["iiif_json"] = json.dumps(resource_data)