Just a comment, some time ago needed to use the (18v) impact driver, but no go. Motor refused to increase rpm, and no force whatsoever at the tool output. With whatever (fully charged) battery.
Ready for throw away, but never doing that before at least 1 inspection. And yes, the grease in the star gear was close to completely solidified (age & humidity, was under freezing temp at the time, impact driver left in the car). The motor had zero chance overcoming that braking effect inside the gearbox.
Dismantled, cleaned and fresh\quality grease = good as new.
Example of star gearbox, used whenever big force\reduction in a confined place is needed. Ref. helicopters.
Got that in many handtools. Also in starter motor of my diesel cars, which have needed clean\regrease as well, old grease combined with carbon powder from brush wear = quite a thick mess.