Disconnect Electrical power: Before working on your garage door opener, disconnect the power in the breaker or unplug the unit to avoid accidental operation and decrease the chance of harm or electrical shock. Signs of a defective limit switch include the door not opening or closing completely, reversing way unexpectedly, https://youtu.be/wSkWTAdm-Gg?si=pR5EXdjVuNYjtHN7