diff --git a/DCC.cpp b/DCC.cpp
index 01c2309..b4b6fc1 100644
--- a/DCC.cpp
+++ b/DCC.cpp
@@ -158,7 +158,7 @@ void DCC::setThrottle2( uint16_t cab, byte speedCode)  {
     b[nB++] = speedCode; // for encoding see setThrottle
 
   }
-  if (speedCode==1) DCCQueue::scheduleEstopPacket(b, nB, 4, cab); // highest priority
+  if ((speedCode & 0x7F) == 1) DCCQueue::scheduleEstopPacket(b, nB, 4, cab); // highest priority
   else DCCQueue::scheduleDCCSpeedPacket( b, nB, 4, cab);
 }
 
diff --git a/DCCQueue.cpp b/DCCQueue.cpp
index 1186bd5..8330e74 100644
--- a/DCCQueue.cpp
+++ b/DCCQueue.cpp
@@ -20,8 +20,10 @@
 
 
 #include "Arduino.h"
+#include "defines.h"
 #include "DCCQueue.h"
 #include "DCCWaveform.h"
+#include "DIAG.h"
 
 // create statics 
 DCCQueue* DCCQueue::lowPriorityQueue=new DCCQueue();
@@ -80,7 +82,8 @@ PendingSlot* DCCQueue::recycleList=nullptr;
     
     void DCCQueue::scheduleEstopPacket(byte* packet, byte length, byte repeats,uint16_t loco) {
         
-        
+        // DIAG(F("DCC ESTOP loco=%d"),loco);
+       
         // kill any existing throttle packets for this loco
         PendingSlot * previous=nullptr;
         auto p=highPriorityQueue->head;
@@ -130,6 +133,7 @@ PendingSlot* DCCQueue::recycleList=nullptr;
             // remove this slot from the queue 
             if (previous) previous->next=p->next;
             else highPriorityQueue->head=p->next;
+            if (!highPriorityQueue->head) highPriorityQueue->tail=nullptr;
             
             // and recycle it.
             recycle(p);     
@@ -166,6 +170,7 @@ PendingSlot* DCCQueue::recycleList=nullptr;
             recycleList=p->next;
         }
         else { 
+            DIAG(F("New DCC queue slot"));
             p=new PendingSlot; // need a queue entry 
         }
         p->next=nullptr;