Sometimes, the magnet on the View Frame handle inches out a bit and touches the base of the View Frame track. When this happens, the guide slips out of place. Simply push the magnet back into the guide handle until it stops.
Now, the guide will not slip because the magnet is just hovering over the track.
This is what happens if the magnet is touching the metal track. To fix this problem, simply push the magnet securely into the guide handle until it stops. When the magnet just hovers above the metal track, it will 'stick' securely!