diff --git a/README.md b/README.md
index 9545196..e6c8fbc 100644
--- a/README.md
+++ b/README.md
@@ -155,7 +155,6 @@ options:
                         Use -d flag to specify device.
   --dump-aie-status <output_file_name>
                         Write AIE status to a file and exit.
-  --no_header           Assume raw core dump without header. Use with -c.
   -d DEV, --device DEV  AIE device [phx,stx,telluride]. Default: telluride
   -o <cxr>, --overlay <cxr>
                         Overlay used by design. Default: 4x4
diff --git a/src/mldebug/backend/core_dump_impl.py b/src/mldebug/backend/core_dump_impl.py
index 0825d20..e66a9db 100644
--- a/src/mldebug/backend/core_dump_impl.py
+++ b/src/mldebug/backend/core_dump_impl.py
@@ -15,7 +15,6 @@
 
 try:
   from .xrt_backend import MlDebug
-
   HAS_XRT_BACKEND = True
 except ImportError:
   HAS_XRT_BACKEND = False
diff --git a/src/mldebug/input_parser.py b/src/mldebug/input_parser.py
index c7c4c90..ba5cb59 100644
--- a/src/mldebug/input_parser.py
+++ b/src/mldebug/input_parser.py
@@ -293,18 +293,28 @@ def set_device(args) -> None:
       None
   """
   endmsg = "\n"
+
+  # Core-dump device comes from the file header. Peek to detect it and to see
+  # if the file even has a header; a headerless dump needs an explicit -d.
+  header_variant = None
+  if getattr(args, "core_dump", None):
+    header_variant = CoreDumpFallbackReader.peek_device(args.core_dump)
+    args.no_header = header_variant is None
+    if args.no_header and not args.device:
+      print(
+        "[ERROR] Core dump file has no readable header. Re-run with -d/--device "
+        "to specify the device (e.g. -d telluride) so the raw dump can be parsed."
+      )
+      cleanup_and_exit(args)
+
   if args.device:
     # User-specified device; honor it as the variant and derive the base.
     args.sub_device = args.device
     args.device = get_base_device(args.device)
   else:
     endmsg = " Use -d to specify a diferent device.\n"
-    variant = None
-
-    # For core dumps, the device is baked into the file header. Detect it now
-    # so the overlay (built before the backend) uses the correct aie_iface.
-    if getattr(args, "core_dump", None) and not getattr(args, "no_header", False):
-      variant = CoreDumpFallbackReader.peek_device(args.core_dump)
+    # Prefer the header-detected device.
+    variant = header_variant
 
     if variant is None:
       variant = _detect_vaiml_variant(args.aie_dir)
diff --git a/src/mldebug/mldebug_cli.py b/src/mldebug/mldebug_cli.py
index 6dd79f4..08cc501 100644
--- a/src/mldebug/mldebug_cli.py
+++ b/src/mldebug/mldebug_cli.py
@@ -242,9 +242,6 @@ def app():
     help="Write AIE status to a file and exit.\n",
     default=None,
   )
-  p.add_argument(
-    "--no_header", action="store_true", help="Assume raw core dump without header. Use with -c."
-  )
   # Hidden Argument
   # 'AIE Device type'
   p.add_argument(
@@ -311,8 +308,9 @@ def app():
     dest="load_script",
     default=None,
     metavar="<filename>",
-    help="Execute a Python script in the advanced shell namespace.\n"
-    "Exits after the script unless -i or -s is also specified.\n",
+    help=_dev_cli_help(
+      "Execute a Python script in the advanced shell namespace.\n"
+    ),
   )
   p.add_argument(
     "-e",
@@ -366,7 +364,7 @@ def app():
       "mock_hang",
       "l2_ifm_dump",
       "text_dump",
-      "l1_ofm_dump",
+      #"l1_ofm_dump",
       "skip_iter",
       "dump_temps",
       "multistamp",
@@ -378,7 +376,7 @@ def app():
     # "layer_status    : Dump AIE status at start of each layer\n"
     # "l2_dump_only    : Dump only L2 buffers\n"
     "l2_ifm_dump     : Dump only L2 IFM buffers\n"
-    "l1_ofm_dump     : Dump L1 ofm buffers in addition to others\n"
+    #"l1_ofm_dump     : Dump L1 ofm buffers in addition to others\n"
     "text_dump       : Dump in text format\n"
     "skip_iter       : Skip iterations in batch mode when possible\n"
     "skip_iter2      : skip_iter using lcp lock.(Telluride only)\n"