Hello Flak, That is how I have always tuned the 4000 (auto ground balance, fast motion and gain at max) as that will give the machine the most amount of interference while it is tuning and then it will pick the clearest channel to work with . Another trick when you have a screamer target and can't tell if it's in the side of the hole or bottom just flip to cancel and kill the gain , you will have to be right on the target to get a signal , play with it on a surface target to find out how much to kill the gain . (Don't forget to switch back to mono or DD)