I use my MXT in relic mode with disc. set between 2 to 3 for 90% of my hunting. I've noticed that with the trigger switch in the middle position the threshhold sounds smooth, but if I decide to flip the trigger into lock position the threshhold gets the usual pulsing/chattering sound. Has anyone else experienced this? It also seems that in the middle position the targets are more clear sounding and I get better ID numbers. If others have noticed this difference, than I would not wonder if it may be time to send the MXT to the doctors office for a checkup.