Position a ladder at the end of the house and climb up. Locate all of the gutter spikes that have come loose and are causing the gutters to sag. Remove all of the spikes by hand. Reposition the ladder down each side of the house and climb up to remove all of the loose spikes from the various locations.
Set the ladder up at the first location where the spike was removed from. Push the screw through the existing hole in the front of the gutter. Cover the screw between the gutter and the wall with a 5-inch ferrule. Slide the ferrule over the gutter screw.
Attach the gutter screw to a power drill and push it up firmly against the fascia on the back of the gutter. Drill the gutter into the fascia until the head of the screw is flush with the gutter. Grip the ferrule over the gutter screw between the gutter and the wall. Using your hand, make sure it is securely in place.
Move the ladder to the next location and install the gutter screw into the existing hole just like the first gutter was installed. Continue down each side of the house installing the gutter screws in place.
Climb off the ladder and visually inspect the gutters. Check to verify they are not sagging and are secure against the wall. Tighten down screws, if necessary.