for a while I haven't had anything deeper than about 4 inches coin wise. what could be happening?
Leenie, first off your statement brings up the question, are you hitting trash/iron/junk targets deeper then 4"?
If you are, then perhaps its not your detector but perhaps the disc pattern you are using.
What disc pattern are you using?
Try all metal (clear screen) punch in deep, and put the sound in const, (one tone for any metal under your coil) then dig everything(but detect very slowly, this is to see if you are hitting deep targets 6"+). See if you pop up some good targets.
The key here is to find out IF, you are hitting targets deeper then 4" junk or not, because if you can hit junk deeper then 4" you should be able to hit anything, including coins at the same or greater depths, if there are any present. You could be just unlucky and hunting barren ground filled with junk.
Try this and let me know.