Just try to clean and re-build the one on your 18V, two-speed, clutched drill/driver....
Compared to other drills I've had to disassemble and work on (like and Black and Decker POS) it was really well designed. But the gearbox? four sets of planetary gears with the two-speed selector, and the interface to the clutch. didn't take the clutch apart though. One set of planetaries had a set of tiny roller bearings inside the plant gear shafts....
