is that spark across the actual plug gap? recently i had a similar problem that turned out to be fouled plugs. it was a tuff troubleshoot cuz the plugs looked clean and new.
Man-- I've had new plugs, sanded off old ones, etc. The spark looks good when I take it out. Thing just wont start. couple huffs and puffs when getting on the starter for a while, but nothing more.
Are the slide in the correct sides? The cutout at the bottom of the slide must face rearward, toward air filter. Another thought is float level set correctly?