Here is what I would do. First make sure the contacts on the simm are nice and clean.Use a pencil eraser, acetone, or even rubbing alcohol. Second if cleaning didn't help, try a different MM II sound board. ( It's worth a chance )
OK I see two different sound simms for IDOJ DSS00030 listed as older, and DSS00058. Looks like I have both of them. Here is the deal of the day, PM me your address and I will send you one of each. Test them and which ever one you don't like send it back to me along with your BAD simm and ten bucks and we will call it even.