diff --git a/src/mididevice.cpp b/src/mididevice.cpp
index b43d272..29dcf3f 100644
--- a/src/mididevice.cpp
+++ b/src/mididevice.cpp
@@ -267,29 +267,56 @@ void CMIDIDevice::MIDIMessageHandler (const u8 *pMessage, size_t nLength, unsign
 	}
 	else
 	{
-		// Handling for Voice Dump Request SysEx
+		// Handle Voice Dump Request SysEx (Format 0)
 		if (nLength == 5 &&
 			pMessage[0] == MIDI_SYSTEM_EXCLUSIVE_BEGIN &&
-			pMessage[1] == 0x43 &&
-			(pMessage[2] & 0xF0) == 0x20 && // Check for Yamaha SysEx with channel
-			pMessage[3] == 0x00 &&
+			pMessage[1] == 0x43 &&  // Yamaha manufacturer ID
+			(pMessage[2] & 0xF0) == 0x20 && // Status byte with channel (0x2n)
+			pMessage[3] == 0x00 &&  // Format 0 (single voice)
 			pMessage[4] == MIDI_SYSTEM_EXCLUSIVE_END) {
-			LOGDBG("Voice Dump Request received for channel %d", pMessage[2] & 0x0F);
-			SendSystemExclusiveVoice(0, nCable, pMessage[2] & 0x0F); // Send voice dump for the requested channel
+			uint8_t channel = pMessage[2] & 0x0F;
+			LOGDBG("Voice Dump Request (Format 0) received for channel %d", channel);
+			
+			// Find TG matching this channel
+			bool found = false;
+			for (unsigned nTG = 0; nTG < m_pConfig->GetToneGenerators(); nTG++) {
+				if (m_ChannelMap[nTG] == channel || m_ChannelMap[nTG] == OmniMode) {
+					SendSystemExclusiveVoice(0, nCable, nTG);
+					found = true;
+					// Don't break here to allow multiple TGs on same channel to respond
+				}
+			}
+			
+			if (!found) {
+				// If no specific TG is found for this channel, respond with TG 0
+				SendSystemExclusiveVoice(0, nCable, 0);
+			}
 			return;
 		}
 
-		// Handling for Mute Operator SysEx
+		// Operator enable/disable SysEx handling - Format F0 43 11 g=0 h=1 1B p F7
+		// Where 1B (27) is parameter for operator on/off
+		// And p is a bitmask for operators (bit 0=OP6, bit 1=OP5, bit 2=OP4, bit 3=OP3, bit 4=OP2, bit 5=OP1)
 		if (nLength == 7 &&
 			pMessage[0] == MIDI_SYSTEM_EXCLUSIVE_BEGIN &&
-			pMessage[1] == 0x43 &&
-			pMessage[2] == 0x11 &&
-			pMessage[3] == 0x01 &&
-			pMessage[4] == 0x1B &&
-			pMessage[5] == 0x2F &&
+			pMessage[1] == 0x43 && // Yamaha manufacturer ID
+			pMessage[2] == 0x11 && // Sub-status byte (parameter change)
+			pMessage[3] == 0x01 && // Format byte (h=1, g=0)
+			pMessage[4] == 0x1B && // Parameter 27 (0x1B) - operator on/off
+			pMessage[5] <= 0x3F && // Value (6-bit mask, 0x00-0x3F valid range)
 			pMessage[6] == MIDI_SYSTEM_EXCLUSIVE_END) {
-			LOGDBG("Mute Operator SysEx received: Operator %d, Value %d", pMessage[4], pMessage[5]);
-			m_pSynthesizer->setOperatorMute(pMessage[4], pMessage[5]);
+			
+			uint8_t operatorMask = pMessage[5];
+			LOGDBG("Operator On/Off SysEx received: Mask 0x%02X", operatorMask);
+
+			// Apply to MIDI channel-specific TGs
+			uint8_t channel = 0; // Default to first channel if not specified
+			
+			// Find TGs to apply this to (apply to all TGs if from UI)
+			for (unsigned nTG = 0; nTG < m_pConfig->GetToneGenerators(); nTG++) {
+				// Set the operator mask directly (no toggling)
+				m_pSynthesizer->setOperatorMask(operatorMask, nTG);
+			}
 			return;
 		}