Apparently it’s that those particular thrusters had not been used in 37 yrs. The article confused me, too. I thought they meant that Voyager 1 had been incommunicado all that time.
I'm guessing it is more sophisticated than “Okay Harry - still no signal, try thruster #3 a titch more.”
I dated a gal back in NJ (heck - she's my wife now!). Her family had a motorized antenna up on the roof, with a little dial by the TV to move it around. If you wanted the news about murder you would aim it towards NYC. For fires you would aim it towards Philadelphia.