Your before pic looks like mine, how did you fix it?
I just bought the Multigame (
ArcadeShop is the cheapest place for it, I think it was about $70 or so shipped), as based on my testing, I figured the ROM sockets were bad, oh, and I also bought a rebuilt power supply, as the voltages were off on mine. In hindsight, I should have just rebuilt it, but at the time TNT Amusements was selling em on eBay pretty cheap...
That being said, it could be a lot of things, I wouldn't assume that the SI Multigame would necessarily fix it. From what I've seen the three biggest issues are that the power supply isn't supplying the right voltage, the ROM chips or sockets are bad, or one or more RAM chips is bad.
I would say the first thing to do is check the power supply to make sure you're getting the proper voltage from it. If you aren't getting a good +5, -5 or +12 that could be the problem (I think the +18v just runs the soundboard, so if that's bad the boards may work, but you would have no sound or at least issues with the sound) If any of the voltages are off, I would either track down a working PS, or rebuild yours.
If the voltage checks out, carefully remove the rom from location H on the board, and turn it back on and see if you are getting a pic like the second one. Those ROM sockets are pretty flaky, so that's a pretty common problem. If you're getting a pic like the second one, then the RAM is
probably good, and you're looking at a ROM issue.
By the way, there's lots of good information on
BrentRadio's website, as well as
Elektronforge.com
Oh yeah, here's a good site too:
http://www.marvin3m.com/video/seawolf.htm
It's for SeaWolf, but they are very similar boards with very similar issues
(Note, to the best of my knowledge this information is accurate, if there are any experts out there that have a better working knowledge of SI, feel free to make any corrections

)