I have a 1951 John Deere B that will be making its way into the restoration thread soon. It has several issues that need attention. One of them is a compression leak around the flywheel side sparkplug. When rotating the engine by hand you can hear air wheezing out from around the plug. New plugs, plug gaskets, and switching the plugs has not fixed this. Everything seems fine looking into the hole. I've seen spark plug thread chasers withe a spring loaded seat cutter on them. Would that help? Any ideas?