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LEGO Technic 42121 Excavator Gearbox Mod

Gearbox Mod: 42121 Heavy Duty Excavator

I've always felt like the gearbox in the LEGO Technic Heavy Duty Exacator was a missed opportunity! No problem! I modified mine to include a distribution! Now, one knob will control both the linear actuators independtly.

Download the complete instructions for the modification: 


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