pete, if youre carefull while heating the sprocket up it shouldnt snap, dont forget its a composite white metal, and should be quite maleable when hot, i would reccomend making a type of clamp/press to force it back into shape when youve heated it up and to keep the heat source to hand when you start to straighten it. i hope this helps, and good luck
Tony

"Er, der kämpft und Lebend davonläuft,
Lebt um einem anderen Tag zu kämpfen".