Was reassembling the keyless works on a Waltham Ruby movement, and it has a c spring that can be a bit of a pain to re-install, it took off, so the search began, the watchmakers desk was thoroughly checked, and the floor was gone over, finally ready to concede defeat, I started going through my parts movements looking for a replacement, so I was looking into the drawer I noticed my shirt pocket, when I wondered, could it have, so I checked my shirt pocket and there it was.
Well I have learned my lesson, when I get a spring that has previously tried to escape the work area, I like to use a clear plastic large ziplok bag, I cut a hole just big enough for my left hand in the bottom and reseal the zip part around my right, try keep the movement in the center of it during the installation, it has saved me plenty of time doing grid searches. Also it is a safe place to practice spring installation, I would always try to pick the end of the spring I was installing, instead I found if I used the tweezers as a pusher and pushed the end it was so much easier!