I have the four channel automotive labscope. It is my 5th scope, so I have experience. I am constantly getting interference in my patterns when using the main channel leads. If I hook up the First Look to channel A, the pattern is crisp and clean but when I use the master leads to hook up a low amp probe or voltage lead, I get tons of interference. With just the master lead only I get interference. I have turned off my lights and pretty much powered down my building, no change. Moving the leads amplifies it. I can never get a clean crisp pattern like I do with my other scopes. One of my scopes has a smoothing button, am I missing this feature? When using the low amp probe I have to ground the negative lead in order to clean the pattern up and it is still not great.