I think we can all be agreed that this is NOT a Bach Minerva - nothing fits in. Stencil most probably, and an old stencil at that - sentimental value, yes, but nothing special. IMHO, your money would be better spent on something more modern for your son (unless he has developed an attachment to this particular horn). Look for a good Olds Ambassador, or if you want to buy new, a student model Yamaha or Jupiter will do fine for quite a number of years. Or even, if you want to make sure your son has an instrument to last a lifetime, go for a Stomvi Forte. (that's not to say that Yammies or Jups don't last as long; just that the Stomvi Forte would have some advantage over a student Yammie or Jup so that he could contentedly play it a lifetime unless he became a professional trumpet player).