Sounds like it was re-powered.
With that said, there likely won't be an exact, factory cable replacement.
First, I would remove the cable and throttle (where you adjust speed).
Soak in oil and try working it loose.
Or, to make a new one to your spec's, IE:
https://www.youtube.com/watch?v=OTDP1XsE9c8 https://www.youtube.com/watch?v=HU2AdibfboA You should be able to find a generic on Flea Bay and modify the end to fit your machine if too long.
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