diff --git a/mhkit/dolfyn/io/base.py b/mhkit/dolfyn/io/base.py
index 5208ca47..c31f5fc0 100644
--- a/mhkit/dolfyn/io/base.py
+++ b/mhkit/dolfyn/io/base.py
@@ -83,6 +83,9 @@ def _handle_nan(data):
     Finds trailing nan's that cause issues in running the rotation
     algorithms and deletes them.
     """
+    if "time" not in data["coords"]:
+        raise Exception("No data recorded in file.")
+
     nan = np.zeros(data["coords"]["time"].shape, dtype=bool)
     l = data["coords"]["time"].size
 
diff --git a/mhkit/dolfyn/io/nortek.py b/mhkit/dolfyn/io/nortek.py
index 0e81a874..3510ef40 100644
--- a/mhkit/dolfyn/io/nortek.py
+++ b/mhkit/dolfyn/io/nortek.py
@@ -262,6 +262,7 @@ def __init__(
             self.config["coord_sys_axes"]
         ]
         da["has_imu"] = 0  # Initiate attribute
+        self._eof = self.pos
         if self.debug:
             logging.info("Init completed")
 
@@ -384,6 +385,7 @@ def findnext(self, do_cs=True):
         if self.endian == "<":
             func = np.uint8
             func2 = lib._bitshift8
+        searching = False
         while True:
             val = unpack(self.endian + "H", self.read(2))[0]
             if np.array(val).astype(func) == 165 and (not do_cs or cs == sum):
@@ -391,6 +393,9 @@ def findnext(self, do_cs=True):
                 return hex(func2(val))
             sum += cs
             cs = val
+            if self.debug and not searching:
+                logging.debug("Scanning every 2 bytes for next datablock...")
+                searching = True
 
     def read_id(self):
         """Read the next 'ID' from the file."""
@@ -456,6 +461,7 @@ def findnextid(self, id):
             id = int(id, 0)
         nowid = None
         while nowid != id:
+            pos = self.pos
             nowid = self.read_id()
             if nowid == 16:
                 shift = 22
@@ -463,6 +469,9 @@ def findnextid(self, id):
                 sz = 2 * unpack(self.endian + "H", self.read(2))[0]
                 shift = sz - 4
             self.f.seek(shift, 1)
+            # If we get stuck in a while loop
+            if self.pos == pos:
+                self.f.seek(2, 1)
         return self.pos
 
     def code_spacing(self, searchcode, iternum=50):
diff --git a/mhkit/dolfyn/io/nortek2.py b/mhkit/dolfyn/io/nortek2.py
index fa0992c3..ea56d40c 100644
--- a/mhkit/dolfyn/io/nortek2.py
+++ b/mhkit/dolfyn/io/nortek2.py
@@ -14,6 +14,9 @@
 from ..time import epoch2dt64, _fill_time_gaps
 
 
+int32_max = np.iinfo(np.int32).max
+
+
 def read_signature(
     filename,
     userdata=True,
@@ -163,7 +166,7 @@ def __init__(
             debug=debug,
             dp=dual_profile,
         )
-        self._reopen(bufsize)
+        self._open(bufsize)
         self.filehead_config = self._read_filehead_config_string()
         self._ens_pos = self._index["pos"][
             lib._boolarray_firstensemble_ping(self._index)
@@ -183,7 +186,7 @@ def _calc_lastblock_iswhole(
         return (self._eof - self._ens_pos[-1]) == standard_blocksize
 
     def _check_nortek(self, endian):
-        self._reopen(10)
+        self._open(10)
         byts = self.f.read(2)
         if endian is None:
             if unpack("<" + "BB", byts) == (165, 10):
@@ -205,8 +208,12 @@ def find_all(s, c):
                 yield idx
                 idx = s.find(c, idx + 1)
 
-        # Open the entire file
-        self._reopen(self._eof)
+        # Open the entire file to find start header
+        if self._eof >= int32_max:
+            init_buffer = int32_max
+        else:
+            init_buffer = self._eof
+        self._open(init_buffer)
         pk = self.f.peek(1)
         # Search for multiple saved headers
         found = [i for i in find_all(pk, b"GETCLOCKSTR")]
@@ -216,7 +223,7 @@ def find_all(s, c):
             start_idx = found[-1] - 11
             return start_idx
 
-    def _reopen(self, bufsize=None):
+    def _open(self, bufsize=None):
         if bufsize is None:
             bufsize = 1000000
         try: