During our first test run we discovered that the hot glue was not sufficient to keep the hall sensors in place. When the motors get hot (this happens when they stall) the hot glue easily melts and the sensors get loose.
We dismantled the whole robot and the motors. After separating the rotor and stater it was easy to glue the hall sensors back in, but this time using epoxy. The epoxy glue should have a higher melting temperature.
After soldering wires to the hall sensors the motors are put back together. Using our scope we could see they are working normally again! Hopefully they won’t come loose this time! ^.^