Thanks for the encouragement and advice, you guys. As I was trying to get space in which to pry, I pulled hard on the strap and the bottom suddenly snapped off (safely). The shafts (?) of the keys, as you know, are metal, and I was surprised to find that several are bent, actually ten of them are bent. So it seems clear that somebody has worked on the keys. Also, some keys are loose, while others are solidly in place. This is not detectable from the top of the keyboard. The high B and B# shafts are noticeably bent. When I depress the B key, the A also depresses, which is clearly due to those two white keys touching each other. Sometime, also, when I depress the C, it sticks to the B and depresses both the A and C. The gaps between the G and A and between the C and D are noticeably wider than they should be. These clearance issues are between the keys themselves, not between the pads. So it seems that the solution should be to narrow the gaps between the key tops of the A and B and those of the B and C. Or to try replacement keys from a junker.
The reeds are in excellent shape on this melodica, which I won on eBay at about $130, and it is otherwise in very good condition. So I don’t mind investing time and/or money in it. In fact, I can live with the problem keys if necessary. I also recently purchased a new old stock Piano 32 from Greece. It’s very nice, but unfortunately it isn’t a smaller version of the Piano 36. Sound and action are not as good.