Removing the old door: Take the case off before removing the rubber door. Grip the door firmly where it attaches to the pump and pull to remove.
Installing a new door: Push the pointed tab into the hole until you feel a snap.
Tip to preserve the cover: The charging port cover swivels 360 degrees around the hole. While charging, make sure you are swiveling the cover rather than bending it backwards to preserve the cover.
You can purchase additional charging port covers by clicking here.
If you are a Tandem pump user whose USB Rubber Door is lost or damaged, you can submit a USB rubber door service request by clicking here.