I don't know if many of you still have your MXT detectors, but if you do this video might help. I know a bunch of us bought them about the same time (2002) and I kept mine (Connie inherited it and is a wizard with the thing, will not use the new version). Anyway, the gold bug still strikes and we're now using it on circular nuggets:
https://youtu.be/jIMohIE26Qk
"Metal Detecting Gold Rings - The Drive In Movie"
Nothing will challenge a detector like a 60 year old drive in, but your old (or new) MXT is still up to it.