Personally, I'd just start replacing the batteries before I even tried to run anything. Wouldn't have to do them all at once, you could just do a few and run only the ones with new batteries. Then replace the rest as you put each one in service.
Depending on when these were manufactured they could be even older than 10 years, unless you pre-ordered them all from the current catalogs at the time.
Also, after sitting that long I would fully lubricate everything according to recommendations in the manual, including checking the grease on the gears, in the gearbox etc.. Sometimes the grease hardens up a bit over time and can cause problems.
Gilly posted while I got sidetracked for a few minutes, I agree with his post!
