Try a different coil, it may have nothing to do with the controls, you could have a bad strain relief at the coil.
You can also skip exchange2 all together.
Download the firmware from Minelab page to your desktop. http://www.minelab.com/usa/metal-detectors/treasure-detectors/ctx-3030?view=downloads
Connect detector to computer using the USB cable, explore you computer and you will see a drive named "Minelab".
Go into it and copy and paste existing file on your desktop just in case you need it in future, (better safe than sorry), now delete the firmware in the Minelab Drive then slide the new firmware you downloaded from Minelab on your desktop into the Minelab drive.
Once downloaded disconnect the USB cable, it will say saving then rebooting, once it reboots select your language and your set to go.