m4 mag broken spring

i wind my mags til they click. i always unload them after play by releasing bb catch at top of mag and letting spring unwind freely. two of my mags springs broke i guess when unloading them. just finished reattaching spring to winding wheel. works now. any of you had this happen? did i unload incorrectly? or maybe i wind to much.

common problem with some brands of mags, the wheels will sometimes spit a tooth or disassemble inside the casing. If you disassemble it, 95% of the time it's a simple re-assembly job with a little tweaking.