The original plug had the idle bar so I think I will try to replace that first. The guy who worked on the engine tuned the high and low end - one at a time, and we put several different plugs in, but we did not have the one with the idle bar.

The manual shows the plug as part number HAN3011 ([link=http://www.hangar-9.com/Products/Default.aspx?ProdID=HAN3011]Super Plug[/link]) does not look like what was taken out. Anyone have a link to the right plug?

Thanks to everyone for your help.