Hi Rich! Welcome to the PC forum!
Yes the inverter in the 2007 model year is the Tripp-Lite brand. We've owned our Phoenix Cruiser 2007 2350 since new so that is why I am familiar with them. You are correct that it likes to make noise randomly, most from the fan running for what seems to be for no reason. Ours used to wake me up at night.CLICK HERE
and read through my thread on this subject matter. Given you own a 2400 instead of a 2350, you might need to remove the 4 screws on the Tripp-Lite control panel and pull it out from the cabinet to unplug the phone jack connector I mention. After reading through the thread, if you have anymore questions, please ask them on that thread to keep it lumped together for others to review years from now when they have the same questions.
I'll try my best to help you through your Tripp-Lite inverter jungle.