When disconnecting connectors from the fuse box or from electrical consumers, pull not by the cable, but by the connector.
Press the locking tab and pull the connector at the same time.
When checking or measuring voltage with a measuring device, insert the tips of the device wire lugs only from the back of the connector (cable side), but in the connector sockets.
To replace the connector terminal, insert a narrow screwdriver from the open side of the connector between the spacer tab and the terminal. Having pressed the spacer lug, pull the connector terminal back by the wire. Insert the new terminal until it snaps into place. Check that the terminal is secure by pulling on the wire.