I'm new to this forum and was pleasantly surprised at the number of knowledgeable members here. Hopefully someone can help diagnose my coil problem. I have two M6's, both about 12-13 years old and have the 9.5 coil and the 4x6 shooter coils. One has less than 10 hours use and the other has 100's of hours use. The most used one had been unused for a few months and when I took it out with the 4x6 coil, it overloaded immediately when I turned the sensitivity level to max. I always run it that way. I took the other (barely used) 4x6 and put it on and same thing. So I took the other M6 and tried both 4x6 coils on it and they overloaded as well. The 9.5 coils have no issues. I took the metal detector to a different location to rule out possible EMI and the same overload issue. After using the detector with the 9.5 for a few weeks I put the unused 4x6 on it and it will work for a while 40-45 minutes and then overload. The heavily used 4x6 won't work at all at high sens. It's got me stumped.