I bought one of these pickups and was aware of them being fragile and would break when someone forgets about the wire connected to the amp and try to move the guitar putting tension on the wire, breaking the pickup. They are fragile, so you MUST remember when it's connected to the amp. I disconnect the two frequently since I don't trust my memory.
About the problem of not being able to close the case, I solved this by cutting a small square out of an old undershirt and folded it several times until I could just barely slide it between the piezo and the guitar body below. This gives it support and has prevented breaking the pickup.
Hope this helps. I realize it's about a year late, but hopefully it will help someone.
Cordoba C 10 Spruce
Cordoba C 10 Cedar