The spike attached rain gutters can at some moment sag and pull away from the boards they are connected to, so you must find a solution to repair this very fast. Actually the seamless guttering system often presents this problem. Because of hard weather conditions the nail-to-wood attachment loosens.
The first way to fix this problem is using gutter screws. You can find these in package of 10 in any hardware store. They are similar to common spike nails except that they have a wider threaded portion than the body of the spike itself. You can’t turn them with a regular screwdriver. You will need a square driver-bit. To complete the look, you can give these screws a paint job, to obtain a smooth appearance.
The second way to fix the problem is to use 5/16-to-3/8″ lag-screws to replace the original spikes. The length could be 7” for residential guttering. For larger areas like barns, warehouses, usually buildings with larger guttering you will need a length of about 8”. The fascia-board holes will be secured by these thick and sturdy threaded lag-screws. They also fit through the original ferrule spacers and you don’t need special wrenches to screw them.
It is actually more important that larger gutters function well, than to look smooth, so you don’t have to worry about the raised hexagonal head shapes of the new lag-screws.