Hello,
On the garage, there is something that looks like asphalt felt, and underneath this, holders for the gutter have been installed. The problem is that the gutter tilts backward, causing the water to overflow at the other end. The previous owner has tried to adjust by pushing up the gutter, but it hasn't helped, rather there's a risk of water flowing back up onto the roof. Since the existing mounts are built into the construction, they can't be adjusted further without tearing up the roof.
The solution seems to be to cut away the existing holders and instead mount new ones a bit lower on the fascia board and adjust the pipe downward. How complicated is this for someone who is fairly handy but has never worked with gutters before? At first glance, it looks simple, but of course, I might have missed something. The alternative is to let craftsmen do it.
I can add that the gutter is about 4-5 meters MAX.