Not sure what you mean by scale lines... but there are two little variable resistors accessable under the battery door, and the one nearest to the Slot-2 opening controls some sort of sync for the top screen. I accidentally bumped it when doing the flashme thing, and my top screen had some funky horizontal banding going on, so I used a tiny slot-screwdriver to twist the variable resistor back and forth till I found the setting that looked best.
If your scale lines are like horizontal banding, you might be able to fix it by adjusting that variable resistor. Of course, your mileage may vary, and if you try this, be careful not to short anything out, if you damage your gear it's not my fault, etc etc.
Good luck.
-Atashi