Unfortunately, the tab on the connector can not be replaced, and it is not a simple matter to clip off the end of the cable and replace it with a new one.
In nearly every case where this has happened, it has been because the cord gets tangled in storage. When the sensor is pulled out, the tab can break off. To prevent this from happening, we recommend that sensors not be stored with the cables wound together.
The good news is that the sensor can still be used, and will have full functionality. It will easily connect to the interface port. It will also be somewhat easier to accidentally pull the sensor from the port.
To make the BTA or BTD connector less easy to pull out of the port during use, we recommend a dab of sugru (moldable silicone adhesive, www.sugru.com) be placed on the tab side of the sensor and let to cure overnight. Once solidified, trim the sugru with a scalpel as needed so that the connector will slide in and out of the socket with a bit of friction to help hold it in place.