As k7 says removing and replacing any socketed rom chips is the first thing to do and easiest. If you're lucky it's just a dirty connection.
Unfortunately as this is a more modern game it's likely all the graphics roms are soldered to the board, so unlikely to be that. The next likely reasons for lines like that are 1: bad mask rom (the rom has failed internally on a data line and needs replaced), or 2: bad connection to one of the surface mount graphics chips.
For 2 - gently press on the square surface mount chips while the game is running and see if the lines change or go away.
For 1 and if the roms are in sockets - find out which roms are the sprites by removing 1 at a time and running the game until you see the sprites change. Then when you know what roms are involved with the sprites swap them around. Yes, this will give you corrupt sprites, but see if the lines stay in the same place on screen (this means the fault is on the graphics custom) or if they move with the tiles (this means the fault is on the rom end).
