Can't get rid of swatch pattern lines

Question

I'm creating a map using a woods pattern swatch in Illustrator. There are straight lines which appear seemingly at random when this pattern fills in the perimeter drawn with the pencil tool. Perhaps it's where the swatch pattern repeats itself, and I can't figure a way to remove these before completion and printing. Help appreciated.

Answer 1

Philip,
Do this.
With nothing selected on the artboard, go to the Swatches palette and drag the Woods pattern swatch into a blank area of the document. The art that gets dropped there is the current definition of that pattern swatch.
If you go to the Layers palette, and expand the triangles, you will see that the backmost object in the definition is a rectangle with no fill, and no stroke. This rectangle defines how the pattern tiles repeat. Any parts outside the rectangle are ignored. Select that rectangle, and delete it, since it is bigger than it should be. (This may be easier if you ungroup the definition first.)
By the way, where did you originally get this pattern? Is it raster or vector? (I don't have the file to look at like Bert did, just his screen shots.)
Zoom in close enough that the pattern definition almost fills your window. (This is to enable positioning the bounding rectangle precisely so that it will stitch correctly.) If it is a vector pattern, turn on Smart Guides to facilitate snapping. (This won't help if it is a raster pattern.)
Take the rectangle tool. If the pattern is vector, mouse down on one of the anchor points of one of the tree shapes near the top left corner, and drag diagonally to that same anchor point of the corresponding lower left shape, like in this closeup:
If it is raster, do the same thing, but there won't be any anchor points to snap to. Just make sure that the rectangle encloses exactly one copy of each pixel. So if a particular tree pixel is just inside on the left, it should be just outside on the right.
Now do a Send to Back on the rectangle you just drew. Make sure that it has no stroke, and no fill. Only unpainted rectangles in the back of the selection are interpreted as tiling boundaries.
If the pattern is vector, then delete any tree shapes that fall completely outside the tiling rectangle. Also delete that bogus black line at the right hand side.
Now select all the remaining tree shapes and your tiling rectangle.
Alt drag them onto the copy of the bad Woods pattern swatch in the Swatches palette to redefine it. (Regular dragging makes a new swatch with the selected, alt-dragging redefines an existing swatch with the selected objects.
Just clicking on the New Swatch button doesn't do either! It makes a new swatch that corresponds to whatever is displayed in the Fill or Stroke proxy in the Color palette. So what you were ending up doing was making a new bad swatch that was exactly like the old bad one, since that was the last color you filled anything with!
Now your pattern definition should be fixed. When you create new shapes and fill them with that swatch, they should tile correctly.