Roof Leak

We've had a roof leak for a little while. I've been trying to find out the cause of it. I've noticed nothing wrong with the shingles on this side of the roof. There is nothing coming up through the roof(vents, skylights, etc) on this side of the house. The shingles hang over the drip edge by what looks like 1/2" and there doesn't appear to be any issues there. I did notice today that two gutter screws are missing in one line of gutter. So there is a gap of probably 6 feet in between screws. The gutter is pulled a little bit away from the fascia in that section. I was up there while it was raining today and didn't notice water actively getting behind there but could that be where the water is getting in? I plan to add some gutter screws and run a line of roof cement in between the last row of shingles and the drip edge just for added tightness and hope that works. Any other suggestions? Thanks a lot.

 

Without knowing where the leak is in the house, we can't help much. Whether the gutters are causing problems with the fascia is a viable question.

 

Been in the attic to check where it's leaking?
Is there a roof to side wall joint?
Ridge vent that may have been cut back to far?
Chimmney?
Picture of the roof would be nice.

 

I have been into the attic. I didn't see any water coming from the peak of the roof down. It seems to be coming from the edge, but the attic narrows too much for me to get in there and see where it's actually coming from. Inside the house, the leak showed up on the ceiling near an exterior wall. During a long rain, it made it's way further into the room and came in from a ceiling fan. I'm working on getting some photos.

 

Here's some photos that I just took. They may not be the best quality as I had to climb a wet tree to take them.

 

It appears that the back edge of the gutter is not completely behind the roof edge. Edging could have been longer or gutter could have been higher. Shingles look pretty lumpy, is there only one layer? Find a seam on the ends of a shingle on that first row. Lift the ends slightly with a prybar. There should be a starter shingle under those seams, and the ends of the starter shingle must NOT line up with the ends of the shingle on top of it. If those butt joints line up that is a sure leak.

The house has no eves / overhang / soffit?