diff --git a/TBF/Properties/AssemblyInfo.cs b/TBF/Properties/AssemblyInfo.cs
index 438946eaa..d1a4ae381 100644
--- a/TBF/Properties/AssemblyInfo.cs
+++ b/TBF/Properties/AssemblyInfo.cs
@@ -32,5 +32,5 @@ using System.Runtime.InteropServices;
 //      Build Number
 //      Revision
 //
-[assembly: AssemblyVersion("3.9.3067.1")]
-[assembly: AssemblyFileVersion("3.9.3067.1")]
+[assembly: AssemblyVersion("3.9.3068.1")]
+[assembly: AssemblyFileVersion("3.9.3068.1")]
diff --git a/TBF/Rig/TestMethods/iPerlCommunication/common/OptoTelegramRaw.cs b/TBF/Rig/TestMethods/iPerlCommunication/common/OptoTelegramRaw.cs
index 9ef2e4d5b..3919bedc9 100644
--- a/TBF/Rig/TestMethods/iPerlCommunication/common/OptoTelegramRaw.cs
+++ b/TBF/Rig/TestMethods/iPerlCommunication/common/OptoTelegramRaw.cs
@@ -230,7 +230,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.common
 			// ---------- VOLUME UNWRAP ----------
 			double v = VolumeRaw;
 
-			if (double.IsNaN(volumeRawExtLast))
+			if (counter == 0 || double.IsNaN(volumeRawExtLast))
 			{
 				VolumeRawExt = volumeRawExtLast = v;
 			}
@@ -249,7 +249,7 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.common
 			}
 
 			// ---------- TIMESTAMP UNWRAP (seconds) ----------
-			if (double.IsNaN(timestampExtLast))
+			if (counter == 0 || double.IsNaN(timestampExtLast))
 			{
 				TimestampExt = timestampExtLast = ts;
 			}
diff --git a/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs b/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs
index 502c11afd..b0dc0b28d 100644
--- a/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs
+++ b/TBF/Rig/TestMethods/iPerlCommunication/iPerlHead/IperlHead.cs
@@ -991,6 +991,9 @@ namespace TBF.Rig.TestMethods.iPerlCommunication.iPerlHead
                 endTelegramIdx[i] = 0;
             }
             TestEndTelegramIx = 0;
+            
+            volumeRawExtLast = double.NaN;
+            timestampExtLast = double.NaN;
 
             if (optoSerialPort != null && optoSerialPort.IsOpen) optoSerialPort.DiscardInBuffer();