Jerry, if you have lines in your finished surface my guess is that it is most likely from inadequate sanding. I know you've gone up to 1200 grit, but p1200 paper is not going to remove a p180 scratch.
It would be good to know what your sanding routine is, but here are some general suggestions for your consideration:
1. Start sanding one grit more coarse than you've been doing.
2. Before sanding lightly scrible over the surface with a pencil. Sand uniformly until the pencil marks are removed. You have now removed a complete micro layer of wood, and you've gotten an idea of how long to sand.
3. Repeat the above with your first grit. It is the most important one.
4. Advance to the next grit. Don't skip grits. Some people would call these half steps, but this is the sequence I use: 60, 80, 100, 120, 150, 180, 240, 320, 400, 600.... (I don't necessarily start with 60).
5. After 180 and finer wipe down the surface with mineral spirits. This cleans off the dust and gives a preview of what a finish will look like and highlights any scratch marks.
After you've gained some confidence, you can skip some steps, e.g. the pencil scrible.