I thought I'd weigh in on the discussion from my experience handling springs and the micro ball bearings. First of all, for the springs, I purchased the spring grabber from Micro-Mark. Here's information about it:
I've used this tool for many years while building Kadee 714 couplers for my HOn3 fleet, and it works very well with the Sergent couplers.
As for the ball bearing, I lightly magnetized a #11 blade on my hobby knife to pick up the ball bearing. I magnetized the blade by touching it to the Sergent uncoupling wand. I can then easily position the ball bearing into the cup on the coupler. With my free hand, I use a tooth pick to hold the ball bearing in place while sliding away the hobby knife. I have yet to lose a ball bearing using this method.
Hope this helps!