Garrett Freedom Ace Plus Picking up Rocks

[brainstormer]

Hi,
I have a little electronics knowledge and I fixed this Garrett Freedom Ace Plus that I found at a thrift shop for $6. I used some denatured alcohol on the circuit board and it worked. I used it for about two hours but I find that
it is picking up rocks galore. Either I've stumbled into a meteorite minefield, or
there is a control problem with the elimination control. I have it all the way up, and I took off the knob to see if the pole of the pot was actually making contact, so it is all the way up. Is there any way to adjust this, and is it known to either pick up too many hot rocks as a detector, or possibly have a part that goes bad? I gather there might be a variable resister in there that I can adjust and I'm about to open it up and check. Thanks for
any help.

[SkiWhiz]

The Garrett Freedom Ace Plus is my wife all time favorite detector. You should of used electronic cleaner instead of denatured alcohol (but that shouldn't hurt anything). You might have the sensitivity set too high, you might have hot rocks, or the ground balance could be set too negative for your ground. Don't have one handy but I think there is an internal ground balance pot. and a threshold pot. If you ever decide to sell give me a shout.

[brainstormer]

Thanks for your reply.

I opened it up and was able to reduce one variable pot inside.
I didn't see any other variable controls inside.

I took it back to the area with the hot rocks and was able to
find one Barber Quarter 1907S in VG condition. Unfortunately,
I kept hitting hot rocks and had only one other real metal find in about
two hours of work. It seems this kind of detector isn't able to
work in an area with hot rocks. Am I right or wrong about that?