Strange happenins after central vac motor replacement

I have a vacuflo 960 central vac. It stopped working, and when I went down to look at it after resetting the switch I got a beautiful light show which told me the brushes on the one motor were bad. I replaced it, but the vaccuum would not work until I shorted the low voltage terminals. That caused it to turn on, and now it works just fine. What did shorting the terminals do? Reset something?

Mine only works when the low voltage terminals are connected. Sticking the metal hose end in the wall socket completes the circuit turning on the motor