A week or so ago I was going hunting with the Omega and had the 10" coil on. Got to the soccer field and couldn't ground balance. It just went bong, bong, bong continuously and rapidly and simply would not ground balance. The detector also seemed somewhat erratic. Checked everything and all to no avail. Changed over to the 11DD coil and it ground balanced perfectly. When I got home I tried the 10" coil again and it still wouldn't gb. Tried both the 11" and also the 5" and both gb fine. Before calling Felix this morning I decided to try the 10" coil one more time. Yeah, some of you guessed it! It worked perfectly. Although the grass was dry the day it wouldn't gb, I also submerged the coil in our pool and it still gb and sounds and runs like it should. Has anybody had a similar situation occur? And if so, did you ever determine the problem? Thanks! HH jim tn