If the engine is fairly new then it should be hard to pull with the pullstart when the glow plug is in. Even when its not new, it should still be hard to pull once every rotation. It shouldn't be easy to pull. And correct me if i'm wrong, but I don't think that WD-40 is the best thing to put in your engine. Also, you shouldn't have to take off the whole heatsink, just the glowplug.