Motor that moves along a cable

Lynxmotion Rovers, Sumo, and Tracked
1

Can someone please point me in the right direction…
I am building a prototype and need a small battery powered motor that can travel bidirectional along a small cable - the motor pulling .5 oz of weight.
Any suggestions?
Thank you
Tevis Messer

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e-clec-tech.com/aerosetwca.html