As Randy has said already use a bare piezo, everyone says even a radioshack piezo to take it out of the case. I believe that your problem. Jay does what Randy says, but jay puts doen a little hot then ads the piezo and covers it with more hot glue.
I have bought around five instruments from Jay at tinyguitars and all he does is hot glue them in brass side against the lid and then covered with hot glue and they are all loud. Just look at some of his videos he has posted and see how loud they ar…
That cover gave me an idea what to do with a large balboa box that has a hole drilled in the middle of it. I had no idea what I could do with the box. It also has a smaller hole which can be used for the jack.
Roger, do you have a trike? I don't do tours, I just ride round town to get exercise. Haven't riden much recently, it has been too bad weather. The weather will be pretty soon, and need to get back in the groove.