diff --git a/lddecode/core.py b/lddecode/core.py
index 364cd25d7..e4c7eb21c 100644
--- a/lddecode/core.py
+++ b/lddecode/core.py
@@ -1660,6 +1660,8 @@ def getLine0(self, validpulses):
             isFirstField_prev = not self.prevfield.isFirstField
             conf_prev = self.prevfield.sync_confidence
 
+        #print(line0loc_local, line0loc_prev, line0loc_next)
+
         # Best case - all three line detectors returned something - perform TOOT using median
         if line0loc_local is not None and line0loc_next is not None and line0loc_prev is not None:
             isFirstField_all = (isFirstField_local + isFirstField_prev + isFirstField_next) >= 2
@@ -1741,6 +1743,7 @@ def compute_linelocs(self):
         self.rawpulses = self.getpulses()
         if self.rawpulses is None or len(self.rawpulses) == 0:
             logging.error("Unable to find any sync pulses, jumping one second")
+            print('x1')
             return None, None, int(self.rf.freq_hz)
 
         self.validpulses = validpulses = self.refinepulses()
@@ -1781,7 +1784,7 @@ def compute_linelocs(self):
                 rlineloc_end = np.round(lineloc_end)
                 lineloc_end_distance = np.abs(lineloc_end - rlineloc_end)
 
-                if p[0] == 0 and lineloc_end_distance < lineloc_distance:
+                if p[0] == 0 and rlineloc > 23 and lineloc_end_distance < lineloc_distance:
                     skip_reached = True
 
                 if skip_reached:
@@ -1800,8 +1803,6 @@ def compute_linelocs(self):
                 if p[0] > 0 or (p[0] == 0 and rlineloc < 10):
                     continue
 
-            #print(p, lineloc, rlineloc)
-
             linelocs_dict[np.round(lineloc)] = p[1].start
             linelocs_dist[np.round(lineloc)] = lineloc_distance
 
@@ -2660,6 +2661,8 @@ def __init__(self, fname_in, fname_out, freader, analog_audio = 0, digital_audio
 
         self.doDOD = doDOD
 
+        self.badfields = None
+
         self.fieldinfo = []
 
         self.leadIn = False
@@ -2799,6 +2802,10 @@ def readfield(self, initphase = False):
         redo = False
         
         while done == False:
+            if redo:
+                # Only allow one redo, no matter what
+                done = True
+
             self.fieldloc = self.fdoffset
             f, offset = self.decodefield(initphase = initphase)
 
@@ -2846,6 +2853,12 @@ def readfield(self, initphase = False):
                     self.fdoffset -= offset
                 else:
                     done = True
+            else:
+                # Probably jumping ahead - delete the previous field so
+                # TBC computations aren't thrown off
+                if self.curfield is not None and self.badfields is None:
+                    self.badfields = (self.curfield, f)
+                self.curfield = None
 
         self.curfield = f
 
diff --git a/lddecode/plot_utils.py b/lddecode/plot_utils.py
index d316bda3a..d3b52c374 100644
--- a/lddecode/plot_utils.py
+++ b/lddecode/plot_utils.py
@@ -230,6 +230,13 @@ def draw_raw_field(self, channel = 'demod'):
     
     return draw_raw_bwimage(cooked, self.inlinelen, len(self.linelocs)-2, vscale=4)
 
+def draw_really_raw_field(self, channel = 'demod'):
+    # Draws the pre-TBC field.  Useful for determining if there's a skip (i.e. issue #509)
+    cooked = self.hz_to_output(self.data['video'][channel])
+    cooked = cooked[:(len(cooked)//self.inlinelen)*self.inlinelen]
+    
+    return draw_raw_bwimage(cooked, self.inlinelen, (len(cooked)//self.inlinelen), vscale=4)
+
 def plotline(field, line, usecs = 63.5, linelocs = None):
 	ls = field.lineslice(line, 0, usecs, linelocs)
 	plt.plot(field.data['video']['demod'][ls])