The actual cleaning off the old gunk (plastic on old gears had "melted" supposedly due to interaction with grease) and popping on the new gears took me all told perhaps 25 minutes tops. Prepping, reading all about it, fretting about messing it up perhaps took a couple of hours.
Of course I did mess up in one aspect - I did not apply grease, which was not at the time (in 2006), but is now, included in the assembly instructions. So I now have the ticking noise to remind of that
