[Alan Brinton]

Sbonelo: It sounds to me like the leak (assuming that there is one) would be somewhere along the bottom of the tube (when you are playing the melodica right side up, probably located at or near the base. By folding or unfolding slightly as the tube bends, a small slit may be opening or closing. However, you didn’t say what happens when you play without the tube, blowing directly into the melodica (preferably without a mouthpiece). But also, you didn’t describe the extra sound. If it’s a whistling sound, it’s probably a break in the tube. If it’s a particular extra note that’s playing, probably at lower volume, then the key that plays that extra note could be sticking slightly. I have had this issue on a couple of melodicas. If it’s that, then turning the keyboard upside down might be enough to loosen the key and release it so it isn’t sounding. If a key is sticking slightly, carefully inserting a thin blade or credit card between keys and prying it gently in one direction or the other might solve the problem by stopping this key from rubbing against one of the adjacent keys. If that’s the problem, then you should notice an unevenness in the spaces between some keys.

When you first get a melodica, it’s worth checking the spacing between keys and adjusting any unevenly spaced keys, which usually can be done as I just described.