Just rebuilt my 43785 . . . and, yes, the little ball bearing went flying, but was eventually found after cleaning the work floor with magnet and flashlight in hand. Exactly the same thing happened last month when I restored a recently purchased Challenger 10601 (you'd think I'd learn by now.)
Anyway . . . I measured the ball bearing while I had everything apart and degreased. It appears to be 1/8" (or 0.125",) but my calipers were telling me it was actually closer to 0.135".
Cleaning hint: I keep a bottle of B100 biodiesel (not to be confused with petroleum diesel) around the shop for metal cleansing. This corn oil product does a great job of cutting through rust and removing decades-old grease muck. It also is easier on the nose and hands than ATF or WD40.
When reassembling, it's time for the white lithium grease . . . especially a dab to keep the ball/spring assembly together. A small flat blade screwdriver is the only tool I needed there and needle nose plier for the spring clips. I also spread a layer of grease around the gears. Once everything is back together, I clip on a large socket, hold onto it and spin the wrench handle around quickly like a party noisemaker in both directions for a few minutes to spread the grease around. Now, this old ratchet feels as smooth as the day I bought it (or my father bought it for me) some 4 decades ago.
Ben in Tucson
Yes, they do help a lot. Anyone rebuilding a ratchet should have one of these tools before they even start the job. Eliminates a ton of aggravation.