Well I got that well and truly wrong.
It was when you mentioned soldering to pin 8 that I assumed you meant a 64 pin Saturn. 32 pin Saturns don't have the twist in the ribbon cable, only 64 pin Saturns do.
Try reseating the ribbon cable and see if that helps.
Did you remove any other connectors when fitting the mod? It's easy to forget to reconnect them.
If neither of my suggestions do anything it could be that the excess solder has damaged the IC or has formed a short that's causing problems. Any chance of getting a picture of your CD board?