In this video, This Old House general contractor Tom Silva shows how to maintain aluminum gutters and downspouts.
How to fix a gutter slope:
1. Unscrew and discard the old gutter brackets.
2. Drive one screw through the rear, center of the gutter to hold it in place.
3. Pull down on the end of the gutter to create the proper pitch toward the downspout. Drive in one screw to hold the gutter in position.
4. Mark the locations of all the rafter tails on the fascia board.
5. Slip new, heavy-duty gutter brackets inside of the gutters. Place one in front of every rafter tail.
6. Screw each bracket through the fascia board and into a rafter tail.
7. Use short aluminum pan-head screws to fasten the downspout elbows to the downspout.
8. Screw an aluminum strap near the upper and lower ends of the downspout.
9. Hold the downspout in position, then screw the straps to the house.
10. Screw through the upper end of downspout and into the downspout outlet.