Claw doesn't open when at the top

our robot has a problem opening the claw. It does not open when it is completely raised or completely lowered. But does open at any other point in the range of motion. Any ideas of how to fix the problem.

Pictures would really help. Do you have any sensors that detect lift state?

There are no sensors on it

Could it be a loose wire? Look at places that will get compressed and/or stretched during movement.

We figured it out, bad motor controller