Few things are more frustrating than yanking a pull cord that won’t budge. The first time it happened to me, I thought the motor was ruined. Turns out, it was just a jammed recoil spring.
I removed the cover, gave the mechanism a good cleaning, and sprayed a little lube on the moving parts. The cord snapped back like new.
Now I keep a spare pull cord in my toolbox — cheap insurance for a common problem