If you have not already found the ATS, it is on the back of the Parallax Power Converter. With the power completely off (disconnected shore line and battery), you need to pull the Parallax out (I put a towel down because it has some sharp edges). Pull it out as far as you can. Depending on how much play is in the connected wires, you may have to tilt the top forward to allow you to get to the back. The ATS (ATS301) is "attached" to the back. I put that in quotes, because it all looks like the same unit. The ATS is inside the bump out box on the back. Once you have it open, with a few wire nuts, it can be straight forward by pass (see previous post). Below is a link to a stock image of the Parallax 7300 with a view of where the ATS is located.