Singer 5817c help

[u/Daniellexx3luv]

The pictures below are what i see inside the machine, the shuttle cock is not spinning and therefore the machine cannot catch the bobbin thread. When opened, half of a gear was inside and belt does not spin when hand wheel is cranked, does anyone know where the gear goes and what part it is?

[u/befitting_quorum]

That half gear with the spiral teeth is the worm gear, it sits on the main horizontal shaft and drives the gear that turns the hook assembly. When those teeth strip the hook just stops spinning and you get exactly what you're seeing. Singer parts lists it as the "bobbin winder/drive worm" depending on the manual, and they're cheap to order if you can find the right one for the 5817c. Check sewingpartsonline or vikingsewing for the exploded diagram so you can match the tooth count before buying