I just picked up a Street Fighter 3: Third Strike cabinet last week and the only known issue at time of purchase was the audio. It cuts out part ways during gameplay, but seems to always work in the demo screen. The seller seemed to think it was due to a loose wire. I haven't had a chance to look inside yet and before I do I will need get through the lock on the back (don't have the key). The cabinet is a converted Williams' Smash TV.
Any ideas what the issue could be?