As far as cleaning it, use a soft brush and remove as much loose dirt as it allows. I use a round tooth pick to get into the crevices, gently removing the loose dirt and then brushing it again. When you post a picture we can see what you are dealing with. Congrats on hunting such a cool spot. Some suggestions I have said before: if you go back there, do not just go after the solid readings. I would dig anything that reads on the positive side (non-iron). Many good targets come in as bouncy signals.