Lift the buckle lock slightly out of its slot in the charging rail, just until the spring is exposed enough that you can grab it with tweezers.

Grab the buckle lock such that the tweezers are around both sides of the lock and holding the spring inside the lock.

When you pull the lock out, the spring can shoot out. Make sure you have a firm grip with the tweezers.

Pull the buckle lock out of its slot in the charging rail.

During reassembly, make sure to move the spring from the old lock to the new one.