the wiggle each item really should work to isolate it, if it is in a wire. Try putting on headphones, run the levels real high and don't put them in front of the speakers. just hold each mic separately and move the cables all over, turning and slightly twisting them. Try all the wires and rotate all the connections if they're rotateable.
I'm guessing wires, either in the mic cables or the battery box. Good luck, it can be really frustrating!
Also, seeing as you have the m10, it had internal mics, so you can just try it alone without the external mics or batt box. Again, headphones on, run levels really high, walk around moving the m10 into various positions. That should eliminate the recorder (except for the jack) from the issue. I'm going to go out on a limb and say the recorder is probably OK.
One other idea. If you have pals with gear, try theirs in your recorder. If not, music stores or electronic stores, or even electronic recyclers might have something you can "try out" right on site and see if that's an issue. Others here may loan you something, especially if you're local.