Contact Sensor (Gen1) registering constantly as tampered

I have contact sensors (generation 1) for my house that I just installed and 4 of the 5 are no issue. One sensor constantly reads as tampered, the only way to clear it is by applying pressure to the sensor while mounted. I have reconfigured it several times but it always defaults to tampered. The case fits perfectly but it seems to have an issue with the clearence on the contact. Anyone lese having this issue or any ideas for repair.