Minimal Maze Woes

We struggle to get this robot to navigate the maze...again...
HAL seems to have a mind of his own.  We tune the code over and over, when HAL completes the challenge as expected or close to it, we celebrate and run the challenge again.  After 6-10 solid runs we feel great and move on...  The next day, we set HAL down with the exact same code from the day before and nothing works the way it did yesterday!!!  How frustrating is that...  We tune, again... HAL finally completes the challenge again, we celebrate!  We move on...  Next day is the same as the day before...  It is like the Bill Murray movie Groundhog Day.  I hope we figure this out before we get to England for #PiWars!