Simple and fast, replacing a 12 V halogen reflector is a snap.
Tighten the ends of the spot between your thumb and forefinger to release the round spring that holds it (to put it back in place, push the spring with your fingertip).
Gently pull the spot to disconnect: reflector and halogen lamp form a whole connected to the porcelain connector by two pins.
Take advantage of this intervention to clean the reflectors.
Do not overemphasize: the reflective surface is very fragile with water.
If the row of spots no longer works, the transformer may be the cause.
To change it, take it out through the opening of a spot by pulling on one of the electric wires.
Never touch a halogen bulb: neither extinguished (alteration of illumination) nor in operation (burn).