Hi sixtyfourbits !
Re: audio crackling... Flipstream recently posted here that his ground loop isolator was plugged in backwards, and even then wasn't quite working right. I hope we haven't gotten a bad batch of those, but it's worth checking the easy stuff... remove your backglass, and you should see the ground loop isolator... it's a little rectangular thing between the PC and the audio amplifier. Make sure the cables in and out of it are secure, and that the cable from the PC is going into the "in(put)" of the isolator, and the "out(put)" cable from the isolator is going into the amplifier.
Re: stuck pixel on the screen... ugh. While you're in the backbox checking the audio connections, you can verify that the cable between the PC and the screen is nice and tight on both sides, but realistically, a single stuck pixel is more likely to be a defect in the LCD. Those happen, sadly, on everything from commercial LCD panels like we use, to consumer laptops.
If you continue to have these issues, please do file a service ticket at <https://www.american-pinball.com/support/service/>, and our service team will be happy to help you. I apologize that your machine wasn't 100% perfect out of the box, but I'm sure we'll be able to get you squared away ASAP. Meanwhile, I hope you and your family have a blast playing the game!