My brother just bought a s/h cannon which has the same problem. I his case I think it was caused by dampness left from when his girlfriend cleaned it to within an inch of its life. Out of the 3 ignitors that weren't working I only managed to get two to work. I wiped the leads to remove some of the dampness, cleaned the electrode abd cheated a little by moving the earth rod(? thing it sparks too) over a little closer to the electrode. For him ,I think whatever generates the spark will have to be changed in order to make it completely reliable.