...I would never let this tape measure anywhere near my kids...
My kids each have a couple of tape measures (the older one has Craftsman brand, and the younger has Husky, so there's no question of who owns which). They've had their own 12 footers (the smaller size has less retraction force, and is easier on little hands) since they were quite little (WELL before they could even read the numbers), which gave me two concerns.
1) pinch injury from a blade hook snapping back at the body
2) cut injury from a blade edge returning at a high rate of speed.
Since both of these could be prevented by a blade that only returns slowly, I just turned down the retraction force on them before gifting them to my kids. This is NOT a task for the inept (it can be a little dangerous), but if you can keep all the parts under control when you remove the screw and open up the case (DO NOT let the spool fall out, or the spring can "explode"), you just take the free end of the tape and unwind it a turn or two off the spool, and then put it back together. If you unwind it too much, it won't retract fully, so just unwind one turn at a time until it no longer has too much spring-back. Each turn you take off will weaken it significantly.
If you're re-tightening a tape measure, just remember that if you wind too many turns on, you may end up where the tape can no longer be fully extended before the internal clock spring is completely compressed.
A couple of years ago, I bought an antique 50' retractable power cord reel (it holds 50' of 12 AWG SJ cord). That came with a pair (side by side) of monstrous clock springs that had to be re-lubricated (that reel was no longer retracting, which is how I got it cheap). That was some experience when one of the springs got out of control in my hands as I was unwinding it.
