Congratulations on the home and barely used central vac! The first thing to do is run through this guide to be sure the basics are working properly (vacuum tank works, valves engage suction, and proper suction at each valve) www.builtinvacuum.com/flowchrt.html
. To test each valve simply use a metal tool to touch the metal contacts INSIDE the 1-1/2" diameter hole. As a side note, the manual is for the 352 as well. Regarding low voltage, each valve as low voltage and some homes have high voltage which is two holes above or below the main suction hole. The holes will be 3/8 inch apart and small. If you don't have electric valves you can always use an electric hose and vacuum by simply buying a "corded" version. That means there is an eight foot pigtail cord attached to the wall end of the hose they plugs into a nearby electrical outlet. Really easy to do and the cord is not something you have to drag around because the wires are integrated into the hose for the entire length. You can check it all out here as well as other compatible parts for Nutone https://builtinvacuum.com/help/nutone/kits.html
. Let us know if you need any other help.