Do you have anything on the end of your brass-block to keep the springs from popping out? Like screws, plate with screws etc. I have seen them on some guitars, but none of my balls have them.
I've never had a problem w/ the springs popping out of the block, they're held in place by tension. If you're having this problem, how many springs do you have installed? Try less springs (I use 2 in my floyd guitars, 3 w/ the vintage trem) and increase the tension on them.
Your probably already know this, but here are a few things you may want to consider if it's "standard" tuning/string tension: 1. If the "front" on the trem plate is raised to high and/or the rear of trem plate on the body too low, it will angle the brass block "in" towards the claw, making it easier for the spring shaft to slide out. 2. Try bending the spring shaft inwards a little. 3. Check brass block insert holes too large and/or spring shaft too thin? 4. Worn springs/cheap springs? 5. not enough/too much spring tension? 5. Claw is moving up and down when you "wammy". all of the above