Quoted from Chitownpinball:
Im also still having issues with the sound. The rca/mini jack issue seems to be whats going on. I lose callouts and low end and I have to mess with the rca jacks and mini jack to get it back.
I just had an issue with losing callouts and the low end of sound. Also, the total volume was much quieter. I'm not sure what you mean by the rca / mini jack, but I had reseated all the audio cables, and it didn't help. I contacted JJP, and they gave me spot on advice. First, on the sound board, which is in the middle right of the metal box in the cabinet, reseat the pink cable. If that doesn't work, see if you have a noise filter that will be attached to the right of the board, cable tied on the right side. It looks like a black box, and one jack goes in and another comes out before going to the board. Bypass the noise filter. If that fixes it, just keep the noise filter bypassed. They told me it was not necessary and was removed from later models.
By the way, this is just another example of excellent JJP support. I thought something major was wrong with my sound. Playing around with things myself didn't fix it. A quick ticket in to JJP, and I received the exact answer within half a day. Awesome as always!