diff --git a/invokeai/app/services/model_install/model_install_default.py b/invokeai/app/services/model_install/model_install_default.py
index 9962009195..e4926ce3bd 100644
--- a/invokeai/app/services/model_install/model_install_default.py
+++ b/invokeai/app/services/model_install/model_install_default.py
@@ -34,6 +34,7 @@ from invokeai.backend.model_manager.config import (
 from invokeai.backend.model_manager.metadata import (
     AnyModelRepoMetadata,
     HuggingFaceMetadataFetch,
+    ModelMetadataFetchBase,
     ModelMetadataWithFiles,
     RemoteModelFile,
 )
@@ -268,13 +269,19 @@ class ModelInstallService(ModelInstallServiceBase):
 
     def wait_for_installs(self, timeout: int = 0) -> List[ModelInstallJob]:  # noqa D102
         """Block until all installation jobs are done."""
+        self.printf("wait_for_installs(): ENTERING")
         start = time.time()
         while len(self._download_cache) > 0:
             if self._downloads_changed_event.wait(timeout=0.25):  # in case we miss an event
                 self._downloads_changed_event.clear()
             if timeout > 0 and time.time() - start > timeout:
                 raise TimeoutError("Timeout exceeded")
+        self.printf(
+            f"wait_for_installs(): install_queue size={self._install_queue.qsize()}, download_cache={self._download_cache}"
+        )
         self._install_queue.join()
+
+        self.printf("wait_for_installs(): EXITING")
         return self._install_jobs
 
     def cancel_job(self, job: ModelInstallJob) -> None:
@@ -425,6 +432,7 @@ class ModelInstallService(ModelInstallServiceBase):
             except Empty:
                 continue
             assert job.local_path is not None
+            self.printf(f"_install_next_item(source={job.source}, id={job.id}")
             try:
                 if job.cancelled:
                     self._signal_job_cancelled(job)
@@ -432,9 +440,7 @@ class ModelInstallService(ModelInstallServiceBase):
                 elif job.errored:
                     self._signal_job_errored(job)
 
-                elif (
-                    job.waiting or job.downloads_done
-                ):
+                elif job.waiting or job.downloads_done:
                     self._register_or_install(job)
 
             except InvalidModelConfigException as excp:
@@ -448,6 +454,7 @@ class ModelInstallService(ModelInstallServiceBase):
                 if job._install_tmpdir is not None:
                     rmtree(job._install_tmpdir)
                 self._install_completed_event.set()
+                self.printf("Signaling task done")
                 self._install_queue.task_done()
 
     def _register_or_install(self, job: ModelInstallJob) -> None:
@@ -793,16 +800,25 @@ class ModelInstallService(ModelInstallServiceBase):
     def _download_complete_callback(self, download_job: DownloadJob) -> None:
         self._logger.info(f"{download_job.source}: model download complete")
         with self._lock:
+            self.printf("_LOCK")
             install_job = self._download_cache[download_job.source]
+            self.printf(
+                f"_download_complete_callback(source={download_job.source}, job={install_job.source}, install_job.id={install_job.id})"
+            )
 
             # are there any more active jobs left in this task?
             if install_job.downloading and all(x.complete for x in install_job.download_parts):
+                self.printf(f"_enqueuing job {install_job.id}")
                 self._signal_job_downloads_done(install_job)
                 self._put_in_queue(install_job)
+                self.printf(f"_enqueued job {install_job.id}")
 
             # Let other threads know that the number of downloads has changed
+            self.printf(f"popping {download_job.source}")
             self._download_cache.pop(download_job.source, None)
             self._downloads_changed_event.set()
+            self.printf("downloads_changed_event is set")
+        self.printf("_UNLOCK")
 
     def _download_error_callback(self, download_job: DownloadJob, excp: Optional[Exception] = None) -> None:
         with self._lock:
@@ -907,7 +923,11 @@ class ModelInstallService(ModelInstallServiceBase):
             self._event_bus.emit_model_install_cancelled(str(job.source), id=job.id)
 
     @staticmethod
-    def get_fetcher_from_url(url: str):
+    def get_fetcher_from_url(url: str) -> ModelMetadataFetchBase:
         if re.match(r"^https?://huggingface.co/[^/]+/[^/]+$", url.lower()):
             return HuggingFaceMetadataFetch
         raise ValueError(f"Unsupported model source: '{url}'")
+
+    @staticmethod
+    def printf(message: str) -> None:
+        print(f"[{time.time():18}] [{threading.get_ident():16}] {message}", flush=True)