So me and my partner built a lift that didn’t work. It was a 4 bar lift where there was 4 bars at the base and it had a claw connected to it to try and lift the soda bottles up. But it didn’t really work because it wouldn’t lift the bottles up. But we figured it was just to heavy to lift the claw up.
I would recommend rubber band tensioners.
You could try changing the gear ratio to make the lift stronger
Use a bigger gear ratio. Put a 12 tooth gear onto the shaft that the motor spins on, and then add a 60 tooth or 84 tooth gear to the shaft that moves the 4 bar lift.