Not a hobby for me. Years ago as a kid, I would disassemble pocket watches, Scotties so don't worry I hurt a good one. On reassembling them I always had left over parts and all but one never worked, the one that worked actually went backwards but I never saved time when I used it. I finally gave up. I have dismantled a couple of junker cameras to see the guts and decided I'd have a better chance working on a Rolls Royce Merlin engine or some rocket.