space shuttle - getting in deeper

So I'm reading postings on forums about sound.  It could be the CPU chip, it could be the main sound processor chip, it could be a faulty op-amp.  I figure the easiest quickest fix is to just replace the two main roms for $10 each.  Worst case if mine aren't bad, they are good to have backups for the future (never know when roms aren't going to be available).  There's a guy out of indiana that sells them, so it shouldn't take long to get here:
http://www.thatpinballplace.com/eproms/index.htm

If it's the sound amplifier, I guess I'm going to have to just start desoldering capacitors until something works.  I'm not so sure someone sells NOS of space shuttle amplifiers.  There is some troubleshooting in the manual about sound not working
http://www.ipdb.org/files/2260/Williams_1984_Space_Shuttle_Manual.pdf

So I might just have to go through it one by one.

One thing I do like about this pin is the fact that it has so much diagnostics built in.  3 self test buttons behind the coin door, and test buttons on the main CPU.  I don't know how modern pins are, but this is the first time I've seen this.

Anyway, here's a quick test of it playing with backglass installed