I'm working on this Echo Blower, model PB-250LN. It has no spark at all. This is what I've done. Checked the primary and secondary sides of the ignition coil (got the specs from Echo). Tested good. Cleaned the coil and magneto contacts and made sure the coil spacing was correct. Changed the woodruff key. Checked the on/off switch for continuity. Tested good. Changed spark plug. Still no fire at all. What am I missing? Thanks!