Hi frenchy, read this thread
http://audiokarma.org/forums/showthread.php?t=30364
which is discussing similar problems. At first I would check whether the horizontal oscillator is working and whether there is a negative voltage at the grid of the horizontal output tube. What is the horizontal output current (measure at the cathode of the horizontal output tube or remove the horizontal fuse and measure the current across the fuse). Be sure that you are not in contact with the +b voltage.
Eckhard