Snapback can occur when the lock’s motor has been over rotated or the gears in the lock become out of sync. We see this most often with LS5i and LS-500i deadbolt locks.
The symptoms of snapback are when the locks deadbolt (if it is happening on a deadbolt model and not a leaver model) does not come fully out of the lock or will not go fully back in the lock. Another symptom of snapback is seen when you try to manually lock the door using the thumb turn and there is tension behind it (this can occur on a deadbolt or leaver model lock). You will feel this when you force the lock into the locked/unlocked position and the deadbolt snaps back when releasing the knob.
Snapback is usually caused when the door has not been shut all the way and the lock is engaged or when the deadbolt is extended and the door is slammed.
Please do not use power tools for this repair. Hand tools should be used to ensure screws are not stripped and damage does not occur to your lock's internal parts.
Remove battery plate and batteries.
Remove the four screws from the interior portion of lock.
Pull the lock body off the door, unhook the power plug, remove the three screws from the silver cover plate, and pull the cover plate off.
Pull the motor straight out of the lock body and leave it loose. Twist the deadbolt handle back and forth 10 - 15 times. Ensure the gears move freely from side to side.
Put the motor back in place. Ensure the electronics board is in place. Twist the deadbolt handle another 5 - 10 times to make sure the gears are still moving appropriately.
Put the cover plate back on with the power cord going back through the slot. Re-screw the three cover plate screws. Once the plate is on, twist the deadbolt handle another 2 - 3 times.
Reconnect the power cord, place the lock body back on door and replace the four support screws. Replace batteries and power the lock back on by pressing a button. Finally, test that the deadbolt opens and retracts appropriately and as expected.