Go kart pull starter help?

well,first i bought a go kart and the pull start was broken so i replaced it with my old one it was working for a bit but when i pulled it some how it wasn't griping on to the propeller that starts the motor so then I removed the pull starter and saw that the metal prongs that pop in and out when you pull the rope got stuck and wouldn't lash out then I fixed that it worked then i put it back and it worked for like 3 pulls then the same problem and this happened again like 10 times and i am wondering why this is happening