The gearbox in the trash compactor is used to pivot the chain that drives the sprocket that raises and lowers the compactor ram. If your trash compactor is not compacting or making grinding noises you may need to replace the gearbox. To replace the gearbox, you will need to disconnect the power supply, uninstall the compactor from the cabinet and disassemble the drawer. This part measures approximately 7” long and is made of metal. This is a genuine OEM part.