IIRC, lines in sprites are usually problems with the 2147 RAMs on the video board. There are usually 8x 2147s, but sometimes 2x 2148s. If you have 2147s, you can pull them and install 2x 2148s or 2149s (at 6B and 6H I believe).
If you have any spare 2147 ram you can overlaying one on top of the original chips and see if you can figure out which one is bad. Just try one at a time till you see the blocks change. It will not fix the image but till tell you what to replace. I have done this for several Galaga boards.