I am writing again about this issue. I never mentioned but it really never corrected. I was imaging in visible light and Ha and the lines dont show when I image in visible light, and very dim on Ha. Now I am doing narrowband a lot with OIII and SII where signal is weaker, the lines are a big problem.
One thing, the lines are moving between months. For example, on 2009 the lines where on top of the image but now in 2012 are more to the center (old problem, I know).
Between one image and the next one, they dont appear to move. At least not an amount that I can perceive.
When I stack and stretch the images, they are awful.
Attached a stacked JPG image, SII data with frames from 2009 and 2012. The line on top was de 2009, the line more to the center is the 2012.
Also a FIT also from SII data, just with the 2012 lines