I have six GU10 240v delighted in very high hallway , they recently tripped ,I reset RCD , everything else came back on but not the downlighters. Changed the dimmer switch no better , changed the 2 lamps I can reach , no better . Went in the loft no obvious damage , they look like they are wired in series , would one of the remaining 4 lamps being blown take out complete circuit. Worked perfectly for ten years so assume not a fundamental fault and had no other changes , any idea welcome