I dropped this off nearly 3 months ago to be serviced. I was finally able to go pick it up yesterday. They said they had to "overhaul" and re-oil it, but really didn't get into specifics. When I dropped it off, its rotor would turn when I'd try to hand-wind it.
Not an unusual fault for the 2824-2 powering the watch. The brass reversing wheels probably wore down. Check out videos by Wristwatch Revival or Vintage Watch Services on Youtube to see what's involved in a service -- they literally need to disassemble and then reassemble the entire watch.
Who is"they" and did you ask them for specifics? Any time I've had work done the invoice is usually very detailed as far as what work was done.