You could reduce the gain some as was said. I do not really understand what you mean when you say "the only way to hunt in man sens is to run .... 9 or 10". What happens if you run it in manual sens at say 25? I guess it depends on the ground and the site you are hunting, but to me you should be nearly rock-stable with a 25 manual sens. This is all sort of a separate issue from false signals off of iron. If in fact you cannot get your machine to stabilize except at low manual sens this may be a problem with the unit that could cause other problems like falsing off of iron excessively.
I don't think there is a detector on the market that does not false off of iron. Normally with the Explorer or any other machine as you hunt you will get a "good" signal that turns into iron once you sweep it at a different angle or center the target directly below the coil. If you are turning down your sens to eliminate this type of signal you are in error. You just have to deal with them, although as you learn the machine you will hear differences between an iron false and a good signal.
In conductive tones with Iron Mask set to a little less than 1/4" on the left of the screen, gain of 7, sens at 20 to 26, you should be able to identify iron false signals by sweeping at 90 degrees (if you get a "good" signal initially, turn 90 deg. and sweep the spot again). The Explorer, working correctly, will null out in 99% of the iron falses (initially or at 90 deg.). In my experience the other 1% will most likely be a bent nail. If you are getting "good" signals from both the initial sweep and at 90 deg. and are digging iron - you most likely have a lemon SE. I had one which ML fixed.
Best of luck and HH - BF